Primitive Type slice
1.0.0 ·Expand description
A dynamically-sized view into a contiguous sequence, [T]
. Contiguous here
means that elements are laid out so that every element is the same
distance from its neighbors.
See also the std::slice
module.
Slices are a view into a block of memory represented as a pointer and a length.
// slicing a Vec
let vec = vec![1, 2, 3];
let int_slice = &vec[..];
// coercing an array to a slice
let str_slice: &[&str] = &["one", "two", "three"];
RunSlices are either mutable or shared. The shared slice type is &[T]
,
while the mutable slice type is &mut [T]
, where T
represents the element
type. For example, you can mutate the block of memory that a mutable slice
points to:
let mut x = [1, 2, 3];
let x = &mut x[..]; // Take a full slice of `x`.
x[1] = 7;
assert_eq!(x, &[1, 7, 3]);
RunAs slices store the length of the sequence they refer to, they have twice
the size of pointers to Sized
types.
Also see the reference on
dynamically sized types.
let pointer_size = std::mem::size_of::<&u8>();
assert_eq!(2 * pointer_size, std::mem::size_of::<&[u8]>());
assert_eq!(2 * pointer_size, std::mem::size_of::<*const [u8]>());
assert_eq!(2 * pointer_size, std::mem::size_of::<Box<[u8]>>());
assert_eq!(2 * pointer_size, std::mem::size_of::<Rc<[u8]>>());
Run§Trait Implementations
Some traits are implemented for slices if the element type implements
that trait. This includes Eq
, Hash
and Ord
.
§Iteration
The slices implement IntoIterator
. The iterator yields references to the
slice elements.
let numbers: &[i32] = &[0, 1, 2];
for n in numbers {
println!("{n} is a number!");
}
RunThe mutable slice yields mutable references to the elements:
let mut scores: &mut [i32] = &mut [7, 8, 9];
for score in scores {
*score += 1;
}
RunThis iterator yields mutable references to the slice’s elements, so while
the element type of the slice is i32
, the element type of the iterator is
&mut i32
.
Implementations§
source§impl<T> Box<[T]>
impl<T> Box<[T]>
sourcepub fn new_uninit_slice(len: usize) -> Box<[MaybeUninit<T>]>
🔬This is a nightly-only experimental API. (new_uninit
#63291)
pub fn new_uninit_slice(len: usize) -> Box<[MaybeUninit<T>]>
new_uninit
#63291)Constructs a new boxed slice with uninitialized contents.
§Examples
#![feature(new_uninit)]
let mut values = Box::<[u32]>::new_uninit_slice(3);
let values = unsafe {
// Deferred initialization:
values[0].as_mut_ptr().write(1);
values[1].as_mut_ptr().write(2);
values[2].as_mut_ptr().write(3);
values.assume_init()
};
assert_eq!(*values, [1, 2, 3])
Runsourcepub fn new_zeroed_slice(len: usize) -> Box<[MaybeUninit<T>]>
🔬This is a nightly-only experimental API. (new_uninit
#63291)
pub fn new_zeroed_slice(len: usize) -> Box<[MaybeUninit<T>]>
new_uninit
#63291)Constructs a new boxed slice with uninitialized contents, with the memory
being filled with 0
bytes.
See MaybeUninit::zeroed
for examples of correct and incorrect usage
of this method.
§Examples
#![feature(new_uninit)]
let values = Box::<[u32]>::new_zeroed_slice(3);
let values = unsafe { values.assume_init() };
assert_eq!(*values, [0, 0, 0])
Runsourcepub fn try_new_uninit_slice(
len: usize
) -> Result<Box<[MaybeUninit<T>]>, AllocError>
🔬This is a nightly-only experimental API. (allocator_api
#32838)
pub fn try_new_uninit_slice( len: usize ) -> Result<Box<[MaybeUninit<T>]>, AllocError>
allocator_api
#32838)Constructs a new boxed slice with uninitialized contents. Returns an error if the allocation fails
§Examples
#![feature(allocator_api, new_uninit)]
let mut values = Box::<[u32]>::try_new_uninit_slice(3)?;
let values = unsafe {
// Deferred initialization:
values[0].as_mut_ptr().write(1);
values[1].as_mut_ptr().write(2);
values[2].as_mut_ptr().write(3);
values.assume_init()
};
assert_eq!(*values, [1, 2, 3]);
Runsourcepub fn try_new_zeroed_slice(
len: usize
) -> Result<Box<[MaybeUninit<T>]>, AllocError>
🔬This is a nightly-only experimental API. (allocator_api
#32838)
pub fn try_new_zeroed_slice( len: usize ) -> Result<Box<[MaybeUninit<T>]>, AllocError>
allocator_api
#32838)Constructs a new boxed slice with uninitialized contents, with the memory
being filled with 0
bytes. Returns an error if the allocation fails
See MaybeUninit::zeroed
for examples of correct and incorrect usage
of this method.
§Examples
#![feature(allocator_api, new_uninit)]
let values = Box::<[u32]>::try_new_zeroed_slice(3)?;
let values = unsafe { values.assume_init() };
assert_eq!(*values, [0, 0, 0]);
Runsource§impl<T, A> Box<[T], A>where
A: Allocator,
impl<T, A> Box<[T], A>where
A: Allocator,
sourcepub fn new_uninit_slice_in(len: usize, alloc: A) -> Box<[MaybeUninit<T>], A>
🔬This is a nightly-only experimental API. (allocator_api
#32838)
pub fn new_uninit_slice_in(len: usize, alloc: A) -> Box<[MaybeUninit<T>], A>
allocator_api
#32838)Constructs a new boxed slice with uninitialized contents in the provided allocator.
§Examples
#![feature(allocator_api, new_uninit)]
use std::alloc::System;
let mut values = Box::<[u32], _>::new_uninit_slice_in(3, System);
let values = unsafe {
// Deferred initialization:
values[0].as_mut_ptr().write(1);
values[1].as_mut_ptr().write(2);
values[2].as_mut_ptr().write(3);
values.assume_init()
};
assert_eq!(*values, [1, 2, 3])
Runsourcepub fn new_zeroed_slice_in(len: usize, alloc: A) -> Box<[MaybeUninit<T>], A>
🔬This is a nightly-only experimental API. (allocator_api
#32838)
pub fn new_zeroed_slice_in(len: usize, alloc: A) -> Box<[MaybeUninit<T>], A>
allocator_api
#32838)Constructs a new boxed slice with uninitialized contents in the provided allocator,
with the memory being filled with 0
bytes.
See MaybeUninit::zeroed
for examples of correct and incorrect usage
of this method.
§Examples
#![feature(allocator_api, new_uninit)]
use std::alloc::System;
let values = Box::<[u32], _>::new_zeroed_slice_in(3, System);
let values = unsafe { values.assume_init() };
assert_eq!(*values, [0, 0, 0])
Runsource§impl<T, A> Box<[MaybeUninit<T>], A>where
A: Allocator,
impl<T, A> Box<[MaybeUninit<T>], A>where
A: Allocator,
sourcepub unsafe fn assume_init(self) -> Box<[T], A>
🔬This is a nightly-only experimental API. (new_uninit
#63291)
pub unsafe fn assume_init(self) -> Box<[T], A>
new_uninit
#63291)Converts to Box<[T], A>
.
§Safety
As with MaybeUninit::assume_init
,
it is up to the caller to guarantee that the values
really are in an initialized state.
Calling this when the content is not yet fully initialized
causes immediate undefined behavior.
§Examples
#![feature(new_uninit)]
let mut values = Box::<[u32]>::new_uninit_slice(3);
let values = unsafe {
// Deferred initialization:
values[0].as_mut_ptr().write(1);
values[1].as_mut_ptr().write(2);
values[2].as_mut_ptr().write(3);
values.assume_init()
};
assert_eq!(*values, [1, 2, 3])
Runsource§impl [u8]
impl [u8]
1.23.0 (const: 1.74.0) · sourcepub const fn is_ascii(&self) -> bool
pub const fn is_ascii(&self) -> bool
Checks if all bytes in this slice are within the ASCII range.
sourcepub const fn as_ascii(&self) -> Option<&[AsciiChar]>
🔬This is a nightly-only experimental API. (ascii_char
#110998)
pub const fn as_ascii(&self) -> Option<&[AsciiChar]>
ascii_char
#110998)If this slice is_ascii
, returns it as a slice of
ASCII characters, otherwise returns None
.
sourcepub const unsafe fn as_ascii_unchecked(&self) -> &[AsciiChar]
🔬This is a nightly-only experimental API. (ascii_char
#110998)
pub const unsafe fn as_ascii_unchecked(&self) -> &[AsciiChar]
ascii_char
#110998)Converts this slice of bytes into a slice of ASCII characters, without checking whether they’re valid.
§Safety
Every byte in the slice must be in 0..=127
, or else this is UB.
1.23.0 · sourcepub fn eq_ignore_ascii_case(&self, other: &[u8]) -> bool
pub fn eq_ignore_ascii_case(&self, other: &[u8]) -> bool
Checks that two slices are an ASCII case-insensitive match.
Same as to_ascii_lowercase(a) == to_ascii_lowercase(b)
,
but without allocating and copying temporaries.
1.23.0 · sourcepub fn make_ascii_uppercase(&mut self)
pub fn make_ascii_uppercase(&mut self)
Converts this slice to its ASCII upper case equivalent in-place.
ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.
To return a new uppercased value without modifying the existing one, use
to_ascii_uppercase
.
1.23.0 · sourcepub fn make_ascii_lowercase(&mut self)
pub fn make_ascii_lowercase(&mut self)
Converts this slice to its ASCII lower case equivalent in-place.
ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.
To return a new lowercased value without modifying the existing one, use
to_ascii_lowercase
.
1.60.0 · sourcepub fn escape_ascii(&self) -> EscapeAscii<'_> ⓘ
pub fn escape_ascii(&self) -> EscapeAscii<'_> ⓘ
sourcepub const fn trim_ascii_start(&self) -> &[u8] ⓘ
🔬This is a nightly-only experimental API. (byte_slice_trim_ascii
#94035)
pub const fn trim_ascii_start(&self) -> &[u8] ⓘ
byte_slice_trim_ascii
#94035)Returns a byte slice with leading ASCII whitespace bytes removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
§Examples
#![feature(byte_slice_trim_ascii)]
assert_eq!(b" \t hello world\n".trim_ascii_start(), b"hello world\n");
assert_eq!(b" ".trim_ascii_start(), b"");
assert_eq!(b"".trim_ascii_start(), b"");
Runsourcepub const fn trim_ascii_end(&self) -> &[u8] ⓘ
🔬This is a nightly-only experimental API. (byte_slice_trim_ascii
#94035)
pub const fn trim_ascii_end(&self) -> &[u8] ⓘ
byte_slice_trim_ascii
#94035)Returns a byte slice with trailing ASCII whitespace bytes removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
§Examples
#![feature(byte_slice_trim_ascii)]
assert_eq!(b"\r hello world\n ".trim_ascii_end(), b"\r hello world");
assert_eq!(b" ".trim_ascii_end(), b"");
assert_eq!(b"".trim_ascii_end(), b"");
Runsourcepub const fn trim_ascii(&self) -> &[u8] ⓘ
🔬This is a nightly-only experimental API. (byte_slice_trim_ascii
#94035)
pub const fn trim_ascii(&self) -> &[u8] ⓘ
byte_slice_trim_ascii
#94035)Returns a byte slice with leading and trailing ASCII whitespace bytes removed.
‘Whitespace’ refers to the definition used by
u8::is_ascii_whitespace
.
§Examples
#![feature(byte_slice_trim_ascii)]
assert_eq!(b"\r hello world\n ".trim_ascii(), b"hello world");
assert_eq!(b" ".trim_ascii(), b"");
assert_eq!(b"".trim_ascii(), b"");
Runsource§impl [f32]
impl [f32]
sourcepub fn sort_floats(&mut self)
🔬This is a nightly-only experimental API. (sort_floats
#93396)
pub fn sort_floats(&mut self)
sort_floats
#93396)Sorts the slice of floats.
This sort is in-place (i.e. does not allocate), O(n * log(n)) worst-case, and uses
the ordering defined by f32::total_cmp
.
§Current implementation
This uses the same sorting algorithm as sort_unstable_by
.
§Examples
#![feature(sort_floats)]
let mut v = [2.6, -5e-8, f32::NAN, 8.29, f32::INFINITY, -1.0, 0.0, -f32::INFINITY, -0.0];
v.sort_floats();
let sorted = [-f32::INFINITY, -1.0, -5e-8, -0.0, 0.0, 2.6, 8.29, f32::INFINITY, f32::NAN];
assert_eq!(&v[..8], &sorted[..8]);
assert!(v[8].is_nan());
Runsource§impl<T, const N: usize> [[T; N]]
impl<T, const N: usize> [[T; N]]
sourcepub const fn flatten(&self) -> &[T]
🔬This is a nightly-only experimental API. (slice_flatten
#95629)
pub const fn flatten(&self) -> &[T]
slice_flatten
#95629)Takes a &[[T; N]]
, and flattens it to a &[T]
.
§Panics
This panics if the length of the resulting slice would overflow a usize
.
This is only possible when flattening a slice of arrays of zero-sized
types, and thus tends to be irrelevant in practice. If
size_of::<T>() > 0
, this will never panic.
§Examples
#![feature(slice_flatten)]
assert_eq!([[1, 2, 3], [4, 5, 6]].flatten(), &[1, 2, 3, 4, 5, 6]);
assert_eq!(
[[1, 2, 3], [4, 5, 6]].flatten(),
[[1, 2], [3, 4], [5, 6]].flatten(),
);
let slice_of_empty_arrays: &[[i32; 0]] = &[[], [], [], [], []];
assert!(slice_of_empty_arrays.flatten().is_empty());
let empty_slice_of_arrays: &[[u32; 10]] = &[];
assert!(empty_slice_of_arrays.flatten().is_empty());
Runsourcepub fn flatten_mut(&mut self) -> &mut [T]
🔬This is a nightly-only experimental API. (slice_flatten
#95629)
pub fn flatten_mut(&mut self) -> &mut [T]
slice_flatten
#95629)Takes a &mut [[T; N]]
, and flattens it to a &mut [T]
.
§Panics
This panics if the length of the resulting slice would overflow a usize
.
This is only possible when flattening a slice of arrays of zero-sized
types, and thus tends to be irrelevant in practice. If
size_of::<T>() > 0
, this will never panic.
§Examples
#![feature(slice_flatten)]
fn add_5_to_all(slice: &mut [i32]) {
for i in slice {
*i += 5;
}
}
let mut array = [[1, 2, 3], [4, 5, 6], [7, 8, 9]];
add_5_to_all(array.flatten_mut());
assert_eq!(array, [[6, 7, 8], [9, 10, 11], [12, 13, 14]]);
Runsource§impl<T> [T]
impl<T> [T]
1.5.0 (const: 1.56.0) · sourcepub const fn split_first(&self) -> Option<(&T, &[T])>
pub const fn split_first(&self) -> Option<(&T, &[T])>
1.5.0 (const: 1.56.0) · sourcepub const fn split_last(&self) -> Option<(&T, &[T])>
pub const fn split_last(&self) -> Option<(&T, &[T])>
1.77.0 (const: 1.77.0) · sourcepub const fn first_chunk<const N: usize>(&self) -> Option<&[T; N]>
pub const fn first_chunk<const N: usize>(&self) -> Option<&[T; N]>
Return an array reference to the first N
items in the slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let u = [10, 40, 30];
assert_eq!(Some(&[10, 40]), u.first_chunk::<2>());
let v: &[i32] = &[10];
assert_eq!(None, v.first_chunk::<2>());
let w: &[i32] = &[];
assert_eq!(Some(&[]), w.first_chunk::<0>());
Run1.77.0 (const: unstable) · sourcepub fn first_chunk_mut<const N: usize>(&mut self) -> Option<&mut [T; N]>
pub fn first_chunk_mut<const N: usize>(&mut self) -> Option<&mut [T; N]>
Return a mutable array reference to the first N
items in the slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let x = &mut [0, 1, 2];
if let Some(first) = x.first_chunk_mut::<2>() {
first[0] = 5;
first[1] = 4;
}
assert_eq!(x, &[5, 4, 2]);
assert_eq!(None, x.first_chunk_mut::<4>());
Run1.77.0 (const: 1.77.0) · sourcepub const fn split_first_chunk<const N: usize>(&self) -> Option<(&[T; N], &[T])>
pub const fn split_first_chunk<const N: usize>(&self) -> Option<(&[T; N], &[T])>
Return an array reference to the first N
items in the slice and the remaining slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let x = &[0, 1, 2];
if let Some((first, elements)) = x.split_first_chunk::<2>() {
assert_eq!(first, &[0, 1]);
assert_eq!(elements, &[2]);
}
assert_eq!(None, x.split_first_chunk::<4>());
Run1.77.0 (const: unstable) · sourcepub fn split_first_chunk_mut<const N: usize>(
&mut self
) -> Option<(&mut [T; N], &mut [T])>
pub fn split_first_chunk_mut<const N: usize>( &mut self ) -> Option<(&mut [T; N], &mut [T])>
Return a mutable array reference to the first N
items in the slice and the remaining
slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let x = &mut [0, 1, 2];
if let Some((first, elements)) = x.split_first_chunk_mut::<2>() {
first[0] = 3;
first[1] = 4;
elements[0] = 5;
}
assert_eq!(x, &[3, 4, 5]);
assert_eq!(None, x.split_first_chunk_mut::<4>());
Run1.77.0 (const: 1.77.0) · sourcepub const fn split_last_chunk<const N: usize>(&self) -> Option<(&[T], &[T; N])>
pub const fn split_last_chunk<const N: usize>(&self) -> Option<(&[T], &[T; N])>
Return an array reference to the last N
items in the slice and the remaining slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let x = &[0, 1, 2];
if let Some((elements, last)) = x.split_last_chunk::<2>() {
assert_eq!(elements, &[0]);
assert_eq!(last, &[1, 2]);
}
assert_eq!(None, x.split_last_chunk::<4>());
Run1.77.0 (const: unstable) · sourcepub fn split_last_chunk_mut<const N: usize>(
&mut self
) -> Option<(&mut [T], &mut [T; N])>
pub fn split_last_chunk_mut<const N: usize>( &mut self ) -> Option<(&mut [T], &mut [T; N])>
Return a mutable array reference to the last N
items in the slice and the remaining
slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let x = &mut [0, 1, 2];
if let Some((elements, last)) = x.split_last_chunk_mut::<2>() {
last[0] = 3;
last[1] = 4;
elements[0] = 5;
}
assert_eq!(x, &[5, 3, 4]);
assert_eq!(None, x.split_last_chunk_mut::<4>());
Run1.77.0 (const: unstable) · sourcepub fn last_chunk<const N: usize>(&self) -> Option<&[T; N]>
pub fn last_chunk<const N: usize>(&self) -> Option<&[T; N]>
Return an array reference to the last N
items in the slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let u = [10, 40, 30];
assert_eq!(Some(&[40, 30]), u.last_chunk::<2>());
let v: &[i32] = &[10];
assert_eq!(None, v.last_chunk::<2>());
let w: &[i32] = &[];
assert_eq!(Some(&[]), w.last_chunk::<0>());
Run1.77.0 (const: unstable) · sourcepub fn last_chunk_mut<const N: usize>(&mut self) -> Option<&mut [T; N]>
pub fn last_chunk_mut<const N: usize>(&mut self) -> Option<&mut [T; N]>
Return a mutable array reference to the last N
items in the slice.
If the slice is not at least N
in length, this will return None
.
§Examples
let x = &mut [0, 1, 2];
if let Some(last) = x.last_chunk_mut::<2>() {
last[0] = 10;
last[1] = 20;
}
assert_eq!(x, &[0, 10, 20]);
assert_eq!(None, x.last_chunk_mut::<4>());
Runsourcepub fn get<I>(&self, index: I) -> Option<&<I as SliceIndex<[T]>>::Output>where
I: SliceIndex<[T]>,
pub fn get<I>(&self, index: I) -> Option<&<I as SliceIndex<[T]>>::Output>where
I: SliceIndex<[T]>,
Returns a reference to an element or subslice depending on the type of index.
- If given a position, returns a reference to the element at that
position or
None
if out of bounds. - If given a range, returns the subslice corresponding to that range,
or
None
if out of bounds.
§Examples
let v = [10, 40, 30];
assert_eq!(Some(&40), v.get(1));
assert_eq!(Some(&[10, 40][..]), v.get(0..2));
assert_eq!(None, v.get(3));
assert_eq!(None, v.get(0..4));
Runsourcepub fn get_mut<I>(
&mut self,
index: I
) -> Option<&mut <I as SliceIndex<[T]>>::Output>where
I: SliceIndex<[T]>,
pub fn get_mut<I>(
&mut self,
index: I
) -> Option<&mut <I as SliceIndex<[T]>>::Output>where
I: SliceIndex<[T]>,
sourcepub unsafe fn get_unchecked<I>(
&self,
index: I
) -> &<I as SliceIndex<[T]>>::Outputwhere
I: SliceIndex<[T]>,
pub unsafe fn get_unchecked<I>(
&self,
index: I
) -> &<I as SliceIndex<[T]>>::Outputwhere
I: SliceIndex<[T]>,
Returns a reference to an element or subslice, without doing bounds checking.
For a safe alternative see get
.
§Safety
Calling this method with an out-of-bounds index is undefined behavior even if the resulting reference is not used.
You can think of this like .get(index).unwrap_unchecked()
. It’s UB
to call .get_unchecked(len)
, even if you immediately convert to a
pointer. And it’s UB to call .get_unchecked(..len + 1)
,
.get_unchecked(..=len)
, or similar.
§Examples
let x = &[1, 2, 4];
unsafe {
assert_eq!(x.get_unchecked(1), &2);
}
Runsourcepub unsafe fn get_unchecked_mut<I>(
&mut self,
index: I
) -> &mut <I as SliceIndex<[T]>>::Outputwhere
I: SliceIndex<[T]>,
pub unsafe fn get_unchecked_mut<I>(
&mut self,
index: I
) -> &mut <I as SliceIndex<[T]>>::Outputwhere
I: SliceIndex<[T]>,
Returns a mutable reference to an element or subslice, without doing bounds checking.
For a safe alternative see get_mut
.
§Safety
Calling this method with an out-of-bounds index is undefined behavior even if the resulting reference is not used.
You can think of this like .get_mut(index).unwrap_unchecked()
. It’s
UB to call .get_unchecked_mut(len)
, even if you immediately convert
to a pointer. And it’s UB to call .get_unchecked_mut(..len + 1)
,
.get_unchecked_mut(..=len)
, or similar.
§Examples
let x = &mut [1, 2, 4];
unsafe {
let elem = x.get_unchecked_mut(1);
*elem = 13;
}
assert_eq!(x, &[1, 13, 4]);
Runconst: 1.32.0 · sourcepub const fn as_ptr(&self) -> *const T
pub const fn as_ptr(&self) -> *const T
Returns a raw pointer to the slice’s buffer.
The caller must ensure that the slice outlives the pointer this function returns, or else it will end up pointing to garbage.
The caller must also ensure that the memory the pointer (non-transitively) points to
is never written to (except inside an UnsafeCell
) using this pointer or any pointer
derived from it. If you need to mutate the contents of the slice, use as_mut_ptr
.
Modifying the container referenced by this slice may cause its buffer to be reallocated, which would also make any pointers to it invalid.
§Examples
let x = &[1, 2, 4];
let x_ptr = x.as_ptr();
unsafe {
for i in 0..x.len() {
assert_eq!(x.get_unchecked(i), &*x_ptr.add(i));
}
}
Runconst: 1.61.0 · sourcepub const fn as_mut_ptr(&mut self) -> *mut T
pub const fn as_mut_ptr(&mut self) -> *mut T
Returns an unsafe mutable pointer to the slice’s buffer.
The caller must ensure that the slice outlives the pointer this function returns, or else it will end up pointing to garbage.
Modifying the container referenced by this slice may cause its buffer to be reallocated, which would also make any pointers to it invalid.
§Examples
let x = &mut [1, 2, 4];
let x_ptr = x.as_mut_ptr();
unsafe {
for i in 0..x.len() {
*x_ptr.add(i) += 2;
}
}
assert_eq!(x, &[3, 4, 6]);
Run1.48.0 (const: 1.61.0) · sourcepub const fn as_ptr_range(&self) -> Range<*const T> ⓘ
pub const fn as_ptr_range(&self) -> Range<*const T> ⓘ
Returns the two raw pointers spanning the slice.
The returned range is half-open, which means that the end pointer points one past the last element of the slice. This way, an empty slice is represented by two equal pointers, and the difference between the two pointers represents the size of the slice.
See as_ptr
for warnings on using these pointers. The end pointer
requires extra caution, as it does not point to a valid element in the
slice.
This function is useful for interacting with foreign interfaces which use two pointers to refer to a range of elements in memory, as is common in C++.
It can also be useful to check if a pointer to an element refers to an element of this slice:
let a = [1, 2, 3];
let x = &a[1] as *const _;
let y = &5 as *const _;
assert!(a.as_ptr_range().contains(&x));
assert!(!a.as_ptr_range().contains(&y));
Run1.48.0 (const: 1.61.0) · sourcepub const fn as_mut_ptr_range(&mut self) -> Range<*mut T> ⓘ
pub const fn as_mut_ptr_range(&mut self) -> Range<*mut T> ⓘ
Returns the two unsafe mutable pointers spanning the slice.
The returned range is half-open, which means that the end pointer points one past the last element of the slice. This way, an empty slice is represented by two equal pointers, and the difference between the two pointers represents the size of the slice.
See as_mut_ptr
for warnings on using these pointers. The end
pointer requires extra caution, as it does not point to a valid element
in the slice.
This function is useful for interacting with foreign interfaces which use two pointers to refer to a range of elements in memory, as is common in C++.
const: unstable · sourcepub fn swap(&mut self, a: usize, b: usize)
pub fn swap(&mut self, a: usize, b: usize)
Swaps two elements in the slice.
If a
equals to b
, it’s guaranteed that elements won’t change value.
§Arguments
- a - The index of the first element
- b - The index of the second element
§Panics
Panics if a
or b
are out of bounds.
§Examples
let mut v = ["a", "b", "c", "d", "e"];
v.swap(2, 4);
assert!(v == ["a", "b", "e", "d", "c"]);
Runconst: unstable · sourcepub unsafe fn swap_unchecked(&mut self, a: usize, b: usize)
🔬This is a nightly-only experimental API. (slice_swap_unchecked
#88539)
pub unsafe fn swap_unchecked(&mut self, a: usize, b: usize)
slice_swap_unchecked
#88539)Swaps two elements in the slice, without doing bounds checking.
For a safe alternative see swap
.
§Arguments
- a - The index of the first element
- b - The index of the second element
§Safety
Calling this method with an out-of-bounds index is undefined behavior.
The caller has to ensure that a < self.len()
and b < self.len()
.
§Examples
#![feature(slice_swap_unchecked)]
let mut v = ["a", "b", "c", "d"];
// SAFETY: we know that 1 and 3 are both indices of the slice
unsafe { v.swap_unchecked(1, 3) };
assert!(v == ["a", "d", "c", "b"]);
Runsourcepub fn windows(&self, size: usize) -> Windows<'_, T> ⓘ
pub fn windows(&self, size: usize) -> Windows<'_, T> ⓘ
Returns an iterator over all contiguous windows of length
size
. The windows overlap. If the slice is shorter than
size
, the iterator returns no values.
§Panics
Panics if size
is 0.
§Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.windows(3);
assert_eq!(iter.next().unwrap(), &['l', 'o', 'r']);
assert_eq!(iter.next().unwrap(), &['o', 'r', 'e']);
assert_eq!(iter.next().unwrap(), &['r', 'e', 'm']);
assert!(iter.next().is_none());
RunIf the slice is shorter than size
:
let slice = ['f', 'o', 'o'];
let mut iter = slice.windows(4);
assert!(iter.next().is_none());
RunThere’s no windows_mut
, as that existing would let safe code violate the
“only one &mut
at a time to the same thing” rule. However, you can sometimes
use Cell::as_slice_of_cells
in
conjunction with windows
to accomplish something similar:
use std::cell::Cell;
let mut array = ['R', 'u', 's', 't', ' ', '2', '0', '1', '5'];
let slice = &mut array[..];
let slice_of_cells: &[Cell<char>] = Cell::from_mut(slice).as_slice_of_cells();
for w in slice_of_cells.windows(3) {
Cell::swap(&w[0], &w[2]);
}
assert_eq!(array, ['s', 't', ' ', '2', '0', '1', '5', 'u', 'R']);
Runsourcepub fn chunks(&self, chunk_size: usize) -> Chunks<'_, T> ⓘ
pub fn chunks(&self, chunk_size: usize) -> Chunks<'_, T> ⓘ
Returns an iterator over chunk_size
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are slices and do not overlap. If chunk_size
does not divide the length of the
slice, then the last chunk will not have length chunk_size
.
See chunks_exact
for a variant of this iterator that returns chunks of always exactly
chunk_size
elements, and rchunks
for the same iterator but starting at the end of the
slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.chunks(2);
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert_eq!(iter.next().unwrap(), &['m']);
assert!(iter.next().is_none());
Runsourcepub fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<'_, T> ⓘ
pub fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<'_, T> ⓘ
Returns an iterator over chunk_size
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are mutable slices, and do not overlap. If chunk_size
does not divide the
length of the slice, then the last chunk will not have length chunk_size
.
See chunks_exact_mut
for a variant of this iterator that returns chunks of always
exactly chunk_size
elements, and rchunks_mut
for the same iterator but starting at
the end of the slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.chunks_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
}
count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 3]);
Run1.31.0 · sourcepub fn chunks_exact(&self, chunk_size: usize) -> ChunksExact<'_, T> ⓘ
pub fn chunks_exact(&self, chunk_size: usize) -> ChunksExact<'_, T> ⓘ
Returns an iterator over chunk_size
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are slices and do not overlap. If chunk_size
does not divide the length of the
slice, then the last up to chunk_size-1
elements will be omitted and can be retrieved
from the remainder
function of the iterator.
Due to each chunk having exactly chunk_size
elements, the compiler can often optimize the
resulting code better than in the case of chunks
.
See chunks
for a variant of this iterator that also returns the remainder as a smaller
chunk, and rchunks_exact
for the same iterator but starting at the end of the slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.chunks_exact(2);
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['m']);
Run1.31.0 · sourcepub fn chunks_exact_mut(&mut self, chunk_size: usize) -> ChunksExactMut<'_, T> ⓘ
pub fn chunks_exact_mut(&mut self, chunk_size: usize) -> ChunksExactMut<'_, T> ⓘ
Returns an iterator over chunk_size
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are mutable slices, and do not overlap. If chunk_size
does not divide the
length of the slice, then the last up to chunk_size-1
elements will be omitted and can be
retrieved from the into_remainder
function of the iterator.
Due to each chunk having exactly chunk_size
elements, the compiler can often optimize the
resulting code better than in the case of chunks_mut
.
See chunks_mut
for a variant of this iterator that also returns the remainder as a
smaller chunk, and rchunks_exact_mut
for the same iterator but starting at the end of
the slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.chunks_exact_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
}
count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 0]);
Runsourcepub const unsafe fn as_chunks_unchecked<const N: usize>(&self) -> &[[T; N]]
🔬This is a nightly-only experimental API. (slice_as_chunks
#74985)
pub const unsafe fn as_chunks_unchecked<const N: usize>(&self) -> &[[T; N]]
slice_as_chunks
#74985)Splits the slice into a slice of N
-element arrays,
assuming that there’s no remainder.
§Safety
This may only be called when
- The slice splits exactly into
N
-element chunks (akaself.len() % N == 0
). N != 0
.
§Examples
#![feature(slice_as_chunks)]
let slice: &[char] = &['l', 'o', 'r', 'e', 'm', '!'];
let chunks: &[[char; 1]] =
// SAFETY: 1-element chunks never have remainder
unsafe { slice.as_chunks_unchecked() };
assert_eq!(chunks, &[['l'], ['o'], ['r'], ['e'], ['m'], ['!']]);
let chunks: &[[char; 3]] =
// SAFETY: The slice length (6) is a multiple of 3
unsafe { slice.as_chunks_unchecked() };
assert_eq!(chunks, &[['l', 'o', 'r'], ['e', 'm', '!']]);
// These would be unsound:
// let chunks: &[[_; 5]] = slice.as_chunks_unchecked() // The slice length is not a multiple of 5
// let chunks: &[[_; 0]] = slice.as_chunks_unchecked() // Zero-length chunks are never allowed
Runsourcepub const fn as_chunks<const N: usize>(&self) -> (&[[T; N]], &[T])
🔬This is a nightly-only experimental API. (slice_as_chunks
#74985)
pub const fn as_chunks<const N: usize>(&self) -> (&[[T; N]], &[T])
slice_as_chunks
#74985)Splits the slice into a slice of N
-element arrays,
starting at the beginning of the slice,
and a remainder slice with length strictly less than N
.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(slice_as_chunks)]
let slice = ['l', 'o', 'r', 'e', 'm'];
let (chunks, remainder) = slice.as_chunks();
assert_eq!(chunks, &[['l', 'o'], ['r', 'e']]);
assert_eq!(remainder, &['m']);
RunIf you expect the slice to be an exact multiple, you can combine
let
-else
with an empty slice pattern:
#![feature(slice_as_chunks)]
let slice = ['R', 'u', 's', 't'];
let (chunks, []) = slice.as_chunks::<2>() else {
panic!("slice didn't have even length")
};
assert_eq!(chunks, &[['R', 'u'], ['s', 't']]);
Runsourcepub const fn as_rchunks<const N: usize>(&self) -> (&[T], &[[T; N]])
🔬This is a nightly-only experimental API. (slice_as_chunks
#74985)
pub const fn as_rchunks<const N: usize>(&self) -> (&[T], &[[T; N]])
slice_as_chunks
#74985)Splits the slice into a slice of N
-element arrays,
starting at the end of the slice,
and a remainder slice with length strictly less than N
.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(slice_as_chunks)]
let slice = ['l', 'o', 'r', 'e', 'm'];
let (remainder, chunks) = slice.as_rchunks();
assert_eq!(remainder, &['l']);
assert_eq!(chunks, &[['o', 'r'], ['e', 'm']]);
Runsourcepub fn array_chunks<const N: usize>(&self) -> ArrayChunks<'_, T, N> ⓘ
🔬This is a nightly-only experimental API. (array_chunks
#74985)
pub fn array_chunks<const N: usize>(&self) -> ArrayChunks<'_, T, N> ⓘ
array_chunks
#74985)Returns an iterator over N
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are array references and do not overlap. If N
does not divide the
length of the slice, then the last up to N-1
elements will be omitted and can be
retrieved from the remainder
function of the iterator.
This method is the const generic equivalent of chunks_exact
.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(array_chunks)]
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.array_chunks();
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['m']);
Runsourcepub const unsafe fn as_chunks_unchecked_mut<const N: usize>(
&mut self
) -> &mut [[T; N]]
🔬This is a nightly-only experimental API. (slice_as_chunks
#74985)
pub const unsafe fn as_chunks_unchecked_mut<const N: usize>( &mut self ) -> &mut [[T; N]]
slice_as_chunks
#74985)Splits the slice into a slice of N
-element arrays,
assuming that there’s no remainder.
§Safety
This may only be called when
- The slice splits exactly into
N
-element chunks (akaself.len() % N == 0
). N != 0
.
§Examples
#![feature(slice_as_chunks)]
let slice: &mut [char] = &mut ['l', 'o', 'r', 'e', 'm', '!'];
let chunks: &mut [[char; 1]] =
// SAFETY: 1-element chunks never have remainder
unsafe { slice.as_chunks_unchecked_mut() };
chunks[0] = ['L'];
assert_eq!(chunks, &[['L'], ['o'], ['r'], ['e'], ['m'], ['!']]);
let chunks: &mut [[char; 3]] =
// SAFETY: The slice length (6) is a multiple of 3
unsafe { slice.as_chunks_unchecked_mut() };
chunks[1] = ['a', 'x', '?'];
assert_eq!(slice, &['L', 'o', 'r', 'a', 'x', '?']);
// These would be unsound:
// let chunks: &[[_; 5]] = slice.as_chunks_unchecked_mut() // The slice length is not a multiple of 5
// let chunks: &[[_; 0]] = slice.as_chunks_unchecked_mut() // Zero-length chunks are never allowed
Runsourcepub const fn as_chunks_mut<const N: usize>(
&mut self
) -> (&mut [[T; N]], &mut [T])
🔬This is a nightly-only experimental API. (slice_as_chunks
#74985)
pub const fn as_chunks_mut<const N: usize>( &mut self ) -> (&mut [[T; N]], &mut [T])
slice_as_chunks
#74985)Splits the slice into a slice of N
-element arrays,
starting at the beginning of the slice,
and a remainder slice with length strictly less than N
.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(slice_as_chunks)]
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
let (chunks, remainder) = v.as_chunks_mut();
remainder[0] = 9;
for chunk in chunks {
*chunk = [count; 2];
count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 9]);
Runsourcepub const fn as_rchunks_mut<const N: usize>(
&mut self
) -> (&mut [T], &mut [[T; N]])
🔬This is a nightly-only experimental API. (slice_as_chunks
#74985)
pub const fn as_rchunks_mut<const N: usize>( &mut self ) -> (&mut [T], &mut [[T; N]])
slice_as_chunks
#74985)Splits the slice into a slice of N
-element arrays,
starting at the end of the slice,
and a remainder slice with length strictly less than N
.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(slice_as_chunks)]
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
let (remainder, chunks) = v.as_rchunks_mut();
remainder[0] = 9;
for chunk in chunks {
*chunk = [count; 2];
count += 1;
}
assert_eq!(v, &[9, 1, 1, 2, 2]);
Runsourcepub fn array_chunks_mut<const N: usize>(&mut self) -> ArrayChunksMut<'_, T, N> ⓘ
🔬This is a nightly-only experimental API. (array_chunks
#74985)
pub fn array_chunks_mut<const N: usize>(&mut self) -> ArrayChunksMut<'_, T, N> ⓘ
array_chunks
#74985)Returns an iterator over N
elements of the slice at a time, starting at the
beginning of the slice.
The chunks are mutable array references and do not overlap. If N
does not divide
the length of the slice, then the last up to N-1
elements will be omitted and
can be retrieved from the into_remainder
function of the iterator.
This method is the const generic equivalent of chunks_exact_mut
.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(array_chunks)]
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.array_chunks_mut() {
*chunk = [count; 2];
count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 0]);
Runsourcepub fn array_windows<const N: usize>(&self) -> ArrayWindows<'_, T, N> ⓘ
🔬This is a nightly-only experimental API. (array_windows
#75027)
pub fn array_windows<const N: usize>(&self) -> ArrayWindows<'_, T, N> ⓘ
array_windows
#75027)Returns an iterator over overlapping windows of N
elements of a slice,
starting at the beginning of the slice.
This is the const generic equivalent of windows
.
If N
is greater than the size of the slice, it will return no windows.
§Panics
Panics if N
is 0. This check will most probably get changed to a compile time
error before this method gets stabilized.
§Examples
#![feature(array_windows)]
let slice = [0, 1, 2, 3];
let mut iter = slice.array_windows();
assert_eq!(iter.next().unwrap(), &[0, 1]);
assert_eq!(iter.next().unwrap(), &[1, 2]);
assert_eq!(iter.next().unwrap(), &[2, 3]);
assert!(iter.next().is_none());
Run1.31.0 · sourcepub fn rchunks(&self, chunk_size: usize) -> RChunks<'_, T> ⓘ
pub fn rchunks(&self, chunk_size: usize) -> RChunks<'_, T> ⓘ
Returns an iterator over chunk_size
elements of the slice at a time, starting at the end
of the slice.
The chunks are slices and do not overlap. If chunk_size
does not divide the length of the
slice, then the last chunk will not have length chunk_size
.
See rchunks_exact
for a variant of this iterator that returns chunks of always exactly
chunk_size
elements, and chunks
for the same iterator but starting at the beginning
of the slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.rchunks(2);
assert_eq!(iter.next().unwrap(), &['e', 'm']);
assert_eq!(iter.next().unwrap(), &['o', 'r']);
assert_eq!(iter.next().unwrap(), &['l']);
assert!(iter.next().is_none());
Run1.31.0 · sourcepub fn rchunks_mut(&mut self, chunk_size: usize) -> RChunksMut<'_, T> ⓘ
pub fn rchunks_mut(&mut self, chunk_size: usize) -> RChunksMut<'_, T> ⓘ
Returns an iterator over chunk_size
elements of the slice at a time, starting at the end
of the slice.
The chunks are mutable slices, and do not overlap. If chunk_size
does not divide the
length of the slice, then the last chunk will not have length chunk_size
.
See rchunks_exact_mut
for a variant of this iterator that returns chunks of always
exactly chunk_size
elements, and chunks_mut
for the same iterator but starting at the
beginning of the slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.rchunks_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
}
count += 1;
}
assert_eq!(v, &[3, 2, 2, 1, 1]);
Run1.31.0 · sourcepub fn rchunks_exact(&self, chunk_size: usize) -> RChunksExact<'_, T> ⓘ
pub fn rchunks_exact(&self, chunk_size: usize) -> RChunksExact<'_, T> ⓘ
Returns an iterator over chunk_size
elements of the slice at a time, starting at the
end of the slice.
The chunks are slices and do not overlap. If chunk_size
does not divide the length of the
slice, then the last up to chunk_size-1
elements will be omitted and can be retrieved
from the remainder
function of the iterator.
Due to each chunk having exactly chunk_size
elements, the compiler can often optimize the
resulting code better than in the case of rchunks
.
See rchunks
for a variant of this iterator that also returns the remainder as a smaller
chunk, and chunks_exact
for the same iterator but starting at the beginning of the
slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.rchunks_exact(2);
assert_eq!(iter.next().unwrap(), &['e', 'm']);
assert_eq!(iter.next().unwrap(), &['o', 'r']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['l']);
Run1.31.0 · sourcepub fn rchunks_exact_mut(&mut self, chunk_size: usize) -> RChunksExactMut<'_, T> ⓘ
pub fn rchunks_exact_mut(&mut self, chunk_size: usize) -> RChunksExactMut<'_, T> ⓘ
Returns an iterator over chunk_size
elements of the slice at a time, starting at the end
of the slice.
The chunks are mutable slices, and do not overlap. If chunk_size
does not divide the
length of the slice, then the last up to chunk_size-1
elements will be omitted and can be
retrieved from the into_remainder
function of the iterator.
Due to each chunk having exactly chunk_size
elements, the compiler can often optimize the
resulting code better than in the case of chunks_mut
.
See rchunks_mut
for a variant of this iterator that also returns the remainder as a
smaller chunk, and chunks_exact_mut
for the same iterator but starting at the beginning
of the slice.
§Panics
Panics if chunk_size
is 0.
§Examples
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;
for chunk in v.rchunks_exact_mut(2) {
for elem in chunk.iter_mut() {
*elem += count;
}
count += 1;
}
assert_eq!(v, &[0, 2, 2, 1, 1]);
Run1.77.0 · sourcepub fn chunk_by<F>(&self, pred: F) -> ChunkBy<'_, T, F> ⓘ
pub fn chunk_by<F>(&self, pred: F) -> ChunkBy<'_, T, F> ⓘ
Returns an iterator over the slice producing non-overlapping runs of elements using the predicate to separate them.
The predicate is called for every pair of consecutive elements,
meaning that it is called on slice[0]
and slice[1]
,
followed by slice[1]
and slice[2]
, and so on.
§Examples
let slice = &[1, 1, 1, 3, 3, 2, 2, 2];
let mut iter = slice.chunk_by(|a, b| a == b);
assert_eq!(iter.next(), Some(&[1, 1, 1][..]));
assert_eq!(iter.next(), Some(&[3, 3][..]));
assert_eq!(iter.next(), Some(&[2, 2, 2][..]));
assert_eq!(iter.next(), None);
RunThis method can be used to extract the sorted subslices:
let slice = &[1, 1, 2, 3, 2, 3, 2, 3, 4];
let mut iter = slice.chunk_by(|a, b| a <= b);
assert_eq!(iter.next(), Some(&[1, 1, 2, 3][..]));
assert_eq!(iter.next(), Some(&[2, 3][..]));
assert_eq!(iter.next(), Some(&[2, 3, 4][..]));
assert_eq!(iter.next(), None);
Run1.77.0 · sourcepub fn chunk_by_mut<F>(&mut self, pred: F) -> ChunkByMut<'_, T, F> ⓘ
pub fn chunk_by_mut<F>(&mut self, pred: F) -> ChunkByMut<'_, T, F> ⓘ
Returns an iterator over the slice producing non-overlapping mutable runs of elements using the predicate to separate them.
The predicate is called for every pair of consecutive elements,
meaning that it is called on slice[0]
and slice[1]
,
followed by slice[1]
and slice[2]
, and so on.
§Examples
let slice = &mut [1, 1, 1, 3, 3, 2, 2, 2];
let mut iter = slice.chunk_by_mut(|a, b| a == b);
assert_eq!(iter.next(), Some(&mut [1, 1, 1][..]));
assert_eq!(iter.next(), Some(&mut [3, 3][..]));
assert_eq!(iter.next(), Some(&mut [2, 2, 2][..]));
assert_eq!(iter.next(), None);
RunThis method can be used to extract the sorted subslices:
let slice = &mut [1, 1, 2, 3, 2, 3, 2, 3, 4];
let mut iter = slice.chunk_by_mut(|a, b| a <= b);
assert_eq!(iter.next(), Some(&mut [1, 1, 2, 3][..]));
assert_eq!(iter.next(), Some(&mut [2, 3][..]));
assert_eq!(iter.next(), Some(&mut [2, 3, 4][..]));
assert_eq!(iter.next(), None);
Runconst: 1.71.0 · sourcepub const fn split_at(&self, mid: usize) -> (&[T], &[T])
pub const fn split_at(&self, mid: usize) -> (&[T], &[T])
Divides one slice into two at an index.
The first will contain all indices from [0, mid)
(excluding
the index mid
itself) and the second will contain all
indices from [mid, len)
(excluding the index len
itself).
§Panics
Panics if mid > len
. For a non-panicking alternative see
split_at_checked
.
§Examples
let v = [1, 2, 3, 4, 5, 6];
{
let (left, right) = v.split_at(0);
assert_eq!(left, []);
assert_eq!(right, [1, 2, 3, 4, 5, 6]);
}
{
let (left, right) = v.split_at(2);
assert_eq!(left, [1, 2]);
assert_eq!(right, [3, 4, 5, 6]);
}
{
let (left, right) = v.split_at(6);
assert_eq!(left, [1, 2, 3, 4, 5, 6]);
assert_eq!(right, []);
}
Runconst: unstable · sourcepub fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T])
pub fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T])
Divides one mutable slice into two at an index.
The first will contain all indices from [0, mid)
(excluding
the index mid
itself) and the second will contain all
indices from [mid, len)
(excluding the index len
itself).
§Panics
Panics if mid > len
. For a non-panicking alternative see
split_at_mut_checked
.
§Examples
let mut v = [1, 0, 3, 0, 5, 6];
let (left, right) = v.split_at_mut(2);
assert_eq!(left, [1, 0]);
assert_eq!(right, [3, 0, 5, 6]);
left[1] = 2;
right[1] = 4;
assert_eq!(v, [1, 2, 3, 4, 5, 6]);
Runconst: 1.77.0 · sourcepub const unsafe fn split_at_unchecked(&self, mid: usize) -> (&[T], &[T])
🔬This is a nightly-only experimental API. (slice_split_at_unchecked
#76014)
pub const unsafe fn split_at_unchecked(&self, mid: usize) -> (&[T], &[T])
slice_split_at_unchecked
#76014)Divides one slice into two at an index, without doing bounds checking.
The first will contain all indices from [0, mid)
(excluding
the index mid
itself) and the second will contain all
indices from [mid, len)
(excluding the index len
itself).
For a safe alternative see split_at
.
§Safety
Calling this method with an out-of-bounds index is undefined behavior
even if the resulting reference is not used. The caller has to ensure that
0 <= mid <= self.len()
.
§Examples
#![feature(slice_split_at_unchecked)]
let v = [1, 2, 3, 4, 5, 6];
unsafe {
let (left, right) = v.split_at_unchecked(0);
assert_eq!(left, []);
assert_eq!(right, [1, 2, 3, 4, 5, 6]);
}
unsafe {
let (left, right) = v.split_at_unchecked(2);
assert_eq!(left, [1, 2]);
assert_eq!(right, [3, 4, 5, 6]);
}
unsafe {
let (left, right) = v.split_at_unchecked(6);
assert_eq!(left, [1, 2, 3, 4, 5, 6]);
assert_eq!(right, []);
}
Runconst: unstable · sourcepub unsafe fn split_at_mut_unchecked(
&mut self,
mid: usize
) -> (&mut [T], &mut [T])
🔬This is a nightly-only experimental API. (slice_split_at_unchecked
#76014)
pub unsafe fn split_at_mut_unchecked( &mut self, mid: usize ) -> (&mut [T], &mut [T])
slice_split_at_unchecked
#76014)Divides one mutable slice into two at an index, without doing bounds checking.
The first will contain all indices from [0, mid)
(excluding
the index mid
itself) and the second will contain all
indices from [mid, len)
(excluding the index len
itself).
For a safe alternative see split_at_mut
.
§Safety
Calling this method with an out-of-bounds index is undefined behavior
even if the resulting reference is not used. The caller has to ensure that
0 <= mid <= self.len()
.
§Examples
#![feature(slice_split_at_unchecked)]
let mut v = [1, 0, 3, 0, 5, 6];
// scoped to restrict the lifetime of the borrows
unsafe {
let (left, right) = v.split_at_mut_unchecked(2);
assert_eq!(left, [1, 0]);
assert_eq!(right, [3, 0, 5, 6]);
left[1] = 2;
right[1] = 4;
}
assert_eq!(v, [1, 2, 3, 4, 5, 6]);
Runconst: unstable · sourcepub fn split_at_checked(&self, mid: usize) -> Option<(&[T], &[T])>
🔬This is a nightly-only experimental API. (split_at_checked
#119128)
pub fn split_at_checked(&self, mid: usize) -> Option<(&[T], &[T])>
split_at_checked
#119128)Divides one slice into two at an index, returning None
if the slice is
too short.
If mid ≤ len
returns a pair of slices where the first will contain all
indices from [0, mid)
(excluding the index mid
itself) and the
second will contain all indices from [mid, len)
(excluding the index
len
itself).
Otherwise, if mid > len
, returns None
.
§Examples
#![feature(split_at_checked)]
let v = [1, -2, 3, -4, 5, -6];
{
let (left, right) = v.split_at_checked(0).unwrap();
assert_eq!(left, []);
assert_eq!(right, [1, -2, 3, -4, 5, -6]);
}
{
let (left, right) = v.split_at_checked(2).unwrap();
assert_eq!(left, [1, -2]);
assert_eq!(right, [3, -4, 5, -6]);
}
{
let (left, right) = v.split_at_checked(6).unwrap();
assert_eq!(left, [1, -2, 3, -4, 5, -6]);
assert_eq!(right, []);
}
assert_eq!(None, v.split_at_checked(7));
Runconst: unstable · sourcepub fn split_at_mut_checked(
&mut self,
mid: usize
) -> Option<(&mut [T], &mut [T])>
🔬This is a nightly-only experimental API. (split_at_checked
#119128)
pub fn split_at_mut_checked( &mut self, mid: usize ) -> Option<(&mut [T], &mut [T])>
split_at_checked
#119128)Divides one mutable slice into two at an index, returning None
if the
slice is too short.
If mid ≤ len
returns a pair of slices where the first will contain all
indices from [0, mid)
(excluding the index mid
itself) and the
second will contain all indices from [mid, len)
(excluding the index
len
itself).
Otherwise, if mid > len
, returns None
.
§Examples
#![feature(split_at_checked)]
let mut v = [1, 0, 3, 0, 5, 6];
if let Some((left, right)) = v.split_at_mut_checked(2) {
assert_eq!(left, [1, 0]);
assert_eq!(right, [3, 0, 5, 6]);
left[1] = 2;
right[1] = 4;
}
assert_eq!(v, [1, 2, 3, 4, 5, 6]);
assert_eq!(None, v.split_at_mut_checked(7));
Runsourcepub fn split<F>(&self, pred: F) -> Split<'_, T, F> ⓘ
pub fn split<F>(&self, pred: F) -> Split<'_, T, F> ⓘ
Returns an iterator over subslices separated by elements that match
pred
. The matched element is not contained in the subslices.
§Examples
let slice = [10, 40, 33, 20];
let mut iter = slice.split(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[10, 40]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());
RunIf the first element is matched, an empty slice will be the first item returned by the iterator. Similarly, if the last element in the slice is matched, an empty slice will be the last item returned by the iterator:
let slice = [10, 40, 33];
let mut iter = slice.split(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[10, 40]);
assert_eq!(iter.next().unwrap(), &[]);
assert!(iter.next().is_none());
RunIf two matched elements are directly adjacent, an empty slice will be present between them:
let slice = [10, 6, 33, 20];
let mut iter = slice.split(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[10]);
assert_eq!(iter.next().unwrap(), &[]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());
Run1.51.0 · sourcepub fn split_inclusive<F>(&self, pred: F) -> SplitInclusive<'_, T, F> ⓘ
pub fn split_inclusive<F>(&self, pred: F) -> SplitInclusive<'_, T, F> ⓘ
Returns an iterator over subslices separated by elements that match
pred
. The matched element is contained in the end of the previous
subslice as a terminator.
§Examples
let slice = [10, 40, 33, 20];
let mut iter = slice.split_inclusive(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[10, 40, 33]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());
RunIf the last element of the slice is matched, that element will be considered the terminator of the preceding slice. That slice will be the last item returned by the iterator.
let slice = [3, 10, 40, 33];
let mut iter = slice.split_inclusive(|num| num % 3 == 0);
assert_eq!(iter.next().unwrap(), &[3]);
assert_eq!(iter.next().unwrap(), &[10, 40, 33]);
assert!(iter.next().is_none());
Run1.51.0 · sourcepub fn split_inclusive_mut<F>(&mut self, pred: F) -> SplitInclusiveMut<'_, T, F> ⓘ
pub fn split_inclusive_mut<F>(&mut self, pred: F) -> SplitInclusiveMut<'_, T, F> ⓘ
Returns an iterator over mutable subslices separated by elements that
match pred
. The matched element is contained in the previous
subslice as a terminator.
§Examples
let mut v = [10, 40, 30, 20, 60, 50];
for group in v.split_inclusive_mut(|num| *num % 3 == 0) {
let terminator_idx = group.len()-1;
group[terminator_idx] = 1;
}
assert_eq!(v, [10, 40, 1, 20, 1, 1]);
Run1.27.0 · sourcepub fn rsplit<F>(&self, pred: F) -> RSplit<'_, T, F> ⓘ
pub fn rsplit<F>(&self, pred: F) -> RSplit<'_, T, F> ⓘ
Returns an iterator over subslices separated by elements that match
pred
, starting at the end of the slice and working backwards.
The matched element is not contained in the subslices.
§Examples
let slice = [11, 22, 33, 0, 44, 55];
let mut iter = slice.rsplit(|num| *num == 0);
assert_eq!(iter.next().unwrap(), &[44, 55]);
assert_eq!(iter.next().unwrap(), &[11, 22, 33]);
assert_eq!(iter.next(), None);
RunAs with split()
, if the first or last element is matched, an empty
slice will be the first (or last) item returned by the iterator.
let v = &[0, 1, 1, 2, 3, 5, 8];
let mut it = v.rsplit(|n| *n % 2 == 0);
assert_eq!(it.next().unwrap(), &[]);
assert_eq!(it.next().unwrap(), &[3, 5]);
assert_eq!(it.next().unwrap(), &[1, 1]);
assert_eq!(it.next().unwrap(), &[]);
assert_eq!(it.next(), None);
Run1.27.0 · sourcepub fn rsplit_mut<F>(&mut self, pred: F) -> RSplitMut<'_, T, F> ⓘ
pub fn rsplit_mut<F>(&mut self, pred: F) -> RSplitMut<'_, T, F> ⓘ
Returns an iterator over mutable subslices separated by elements that
match pred
, starting at the end of the slice and working
backwards. The matched element is not contained in the subslices.
§Examples
let mut v = [100, 400, 300, 200, 600, 500];
let mut count = 0;
for group in v.rsplit_mut(|num| *num % 3 == 0) {
count += 1;
group[0] = count;
}
assert_eq!(v, [3, 400, 300, 2, 600, 1]);
Runsourcepub fn splitn<F>(&self, n: usize, pred: F) -> SplitN<'_, T, F> ⓘ
pub fn splitn<F>(&self, n: usize, pred: F) -> SplitN<'_, T, F> ⓘ
Returns an iterator over subslices separated by elements that match
pred
, limited to returning at most n
items. The matched element is
not contained in the subslices.
The last element returned, if any, will contain the remainder of the slice.
§Examples
Print the slice split once by numbers divisible by 3 (i.e., [10, 40]
,
[20, 60, 50]
):
let v = [10, 40, 30, 20, 60, 50];
for group in v.splitn(2, |num| *num % 3 == 0) {
println!("{group:?}");
}
Runsourcepub fn splitn_mut<F>(&mut self, n: usize, pred: F) -> SplitNMut<'_, T, F> ⓘ
pub fn splitn_mut<F>(&mut self, n: usize, pred: F) -> SplitNMut<'_, T, F> ⓘ
Returns an iterator over mutable subslices separated by elements that match
pred
, limited to returning at most n
items. The matched element is
not contained in the subslices.
The last element returned, if any, will contain the remainder of the slice.
§Examples
let mut v = [10, 40, 30, 20, 60, 50];
for group in v.splitn_mut(2, |num| *num % 3 == 0) {
group[0] = 1;
}
assert_eq!(v, [1, 40, 30, 1, 60, 50]);
Runsourcepub fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<'_, T, F> ⓘ
pub fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<'_, T, F> ⓘ
Returns an iterator over subslices separated by elements that match
pred
limited to returning at most n
items. This starts at the end of
the slice and works backwards. The matched element is not contained in
the subslices.
The last element returned, if any, will contain the remainder of the slice.
§Examples
Print the slice split once, starting from the end, by numbers divisible
by 3 (i.e., [50]
, [10, 40, 30, 20]
):
let v = [10, 40, 30, 20, 60, 50];
for group in v.rsplitn(2, |num| *num % 3 == 0) {
println!("{group:?}");
}
Runsourcepub fn rsplitn_mut<F>(&mut self, n: usize, pred: F) -> RSplitNMut<'_, T, F> ⓘ
pub fn rsplitn_mut<F>(&mut self, n: usize, pred: F) -> RSplitNMut<'_, T, F> ⓘ
Returns an iterator over subslices separated by elements that match
pred
limited to returning at most n
items. This starts at the end of
the slice and works backwards. The matched element is not contained in
the subslices.
The last element returned, if any, will contain the remainder of the slice.
§Examples
let mut s = [10, 40, 30, 20, 60, 50];
for group in s.rsplitn_mut(2, |num| *num % 3 == 0) {
group[0] = 1;
}
assert_eq!(s, [1, 40, 30, 20, 60, 1]);
Runsourcepub fn split_once<F>(&self, pred: F) -> Option<(&[T], &[T])>
🔬This is a nightly-only experimental API. (slice_split_once
#112811)
pub fn split_once<F>(&self, pred: F) -> Option<(&[T], &[T])>
slice_split_once
#112811)Splits the slice on the first element that matches the specified predicate.
If any matching elements are present in the slice, returns the prefix
before the match and suffix after. The matching element itself is not
included. If no elements match, returns None
.
§Examples
#![feature(slice_split_once)]
let s = [1, 2, 3, 2, 4];
assert_eq!(s.split_once(|&x| x == 2), Some((
&[1][..],
&[3, 2, 4][..]
)));
assert_eq!(s.split_once(|&x| x == 0), None);
Runsourcepub fn rsplit_once<F>(&self, pred: F) -> Option<(&[T], &[T])>
🔬This is a nightly-only experimental API. (slice_split_once
#112811)
pub fn rsplit_once<F>(&self, pred: F) -> Option<(&[T], &[T])>
slice_split_once
#112811)Splits the slice on the last element that matches the specified predicate.
If any matching elements are present in the slice, returns the prefix
before the match and suffix after. The matching element itself is not
included. If no elements match, returns None
.
§Examples
#![feature(slice_split_once)]
let s = [1, 2, 3, 2, 4];
assert_eq!(s.rsplit_once(|&x| x == 2), Some((
&[1, 2, 3][..],
&[4][..]
)));
assert_eq!(s.rsplit_once(|&x| x == 0), None);
Runsourcepub fn contains(&self, x: &T) -> boolwhere
T: PartialEq,
pub fn contains(&self, x: &T) -> boolwhere
T: PartialEq,
Returns true
if the slice contains an element with the given value.
This operation is O(n).
Note that if you have a sorted slice, binary_search
may be faster.
§Examples
let v = [10, 40, 30];
assert!(v.contains(&30));
assert!(!v.contains(&50));
RunIf you do not have a &T
, but some other value that you can compare
with one (for example, String
implements PartialEq<str>
), you can
use iter().any
:
let v = [String::from("hello"), String::from("world")]; // slice of `String`
assert!(v.iter().any(|e| e == "hello")); // search with `&str`
assert!(!v.iter().any(|e| e == "hi"));
Runsourcepub fn starts_with(&self, needle: &[T]) -> boolwhere
T: PartialEq,
pub fn starts_with(&self, needle: &[T]) -> boolwhere
T: PartialEq,
Returns true
if needle
is a prefix of the slice.
§Examples
let v = [10, 40, 30];
assert!(v.starts_with(&[10]));
assert!(v.starts_with(&[10, 40]));
assert!(!v.starts_with(&[50]));
assert!(!v.starts_with(&[10, 50]));
RunAlways returns true
if needle
is an empty slice:
let v = &[10, 40, 30];
assert!(v.starts_with(&[]));
let v: &[u8] = &[];
assert!(v.starts_with(&[]));
Runsourcepub fn ends_with(&self, needle: &[T]) -> boolwhere
T: PartialEq,
pub fn ends_with(&self, needle: &[T]) -> boolwhere
T: PartialEq,
Returns true
if needle
is a suffix of the slice.
§Examples
let v = [10, 40, 30];
assert!(v.ends_with(&[30]));
assert!(v.ends_with(&[40, 30]));
assert!(!v.ends_with(&[50]));
assert!(!v.ends_with(&[50, 30]));
RunAlways returns true
if needle
is an empty slice:
let v = &[10, 40, 30];
assert!(v.ends_with(&[]));
let v: &[u8] = &[];
assert!(v.ends_with(&[]));
Run1.51.0 · sourcepub fn strip_prefix<P>(&self, prefix: &P) -> Option<&[T]>
pub fn strip_prefix<P>(&self, prefix: &P) -> Option<&[T]>
Returns a subslice with the prefix removed.
If the slice starts with prefix
, returns the subslice after the prefix, wrapped in Some
.
If prefix
is empty, simply returns the original slice.
If the slice does not start with prefix
, returns None
.
§Examples
let v = &[10, 40, 30];
assert_eq!(v.strip_prefix(&[10]), Some(&[40, 30][..]));
assert_eq!(v.strip_prefix(&[10, 40]), Some(&[30][..]));
assert_eq!(v.strip_prefix(&[50]), None);
assert_eq!(v.strip_prefix(&[10, 50]), None);
let prefix : &str = "he";
assert_eq!(b"hello".strip_prefix(prefix.as_bytes()),
Some(b"llo".as_ref()));
Run1.51.0 · sourcepub fn strip_suffix<P>(&self, suffix: &P) -> Option<&[T]>
pub fn strip_suffix<P>(&self, suffix: &P) -> Option<&[T]>
Returns a subslice with the suffix removed.
If the slice ends with suffix
, returns the subslice before the suffix, wrapped in Some
.
If suffix
is empty, simply returns the original slice.
If the slice does not end with suffix
, returns None
.
§Examples
let v = &[10, 40, 30];
assert_eq!(v.strip_suffix(&[30]), Some(&[10, 40][..]));
assert_eq!(v.strip_suffix(&[40, 30]), Some(&[10][..]));
assert_eq!(v.strip_suffix(&[50]), None);
assert_eq!(v.strip_suffix(&[50, 30]), None);
Runsourcepub fn binary_search(&self, x: &T) -> Result<usize, usize>where
T: Ord,
pub fn binary_search(&self, x: &T) -> Result<usize, usize>where
T: Ord,
Binary searches this slice for a given element. If the slice is not sorted, the returned result is unspecified and meaningless.
If the value is found then Result::Ok
is returned, containing the
index of the matching element. If there are multiple matches, then any
one of the matches could be returned. The index is chosen
deterministically, but is subject to change in future versions of Rust.
If the value is not found then Result::Err
is returned, containing
the index where a matching element could be inserted while maintaining
sorted order.
See also binary_search_by
, binary_search_by_key
, and partition_point
.
§Examples
Looks up a series of four elements. The first is found, with a
uniquely determined position; the second and third are not
found; the fourth could match any position in [1, 4]
.
let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
assert_eq!(s.binary_search(&13), Ok(9));
assert_eq!(s.binary_search(&4), Err(7));
assert_eq!(s.binary_search(&100), Err(13));
let r = s.binary_search(&1);
assert!(match r { Ok(1..=4) => true, _ => false, });
RunIf you want to find that whole range of matching items, rather than
an arbitrary matching one, that can be done using partition_point
:
let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let low = s.partition_point(|x| x < &1);
assert_eq!(low, 1);
let high = s.partition_point(|x| x <= &1);
assert_eq!(high, 5);
let r = s.binary_search(&1);
assert!((low..high).contains(&r.unwrap()));
assert!(s[..low].iter().all(|&x| x < 1));
assert!(s[low..high].iter().all(|&x| x == 1));
assert!(s[high..].iter().all(|&x| x > 1));
// For something not found, the "range" of equal items is empty
assert_eq!(s.partition_point(|x| x < &11), 9);
assert_eq!(s.partition_point(|x| x <= &11), 9);
assert_eq!(s.binary_search(&11), Err(9));
RunIf you want to insert an item to a sorted vector, while maintaining
sort order, consider using partition_point
:
let mut s = vec![0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let num = 42;
let idx = s.partition_point(|&x| x < num);
// The above is equivalent to `let idx = s.binary_search(&num).unwrap_or_else(|x| x);`
s.insert(idx, num);
assert_eq!(s, [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 42, 55]);
Runsourcepub fn binary_search_by<'a, F>(&'a self, f: F) -> Result<usize, usize>
pub fn binary_search_by<'a, F>(&'a self, f: F) -> Result<usize, usize>
Binary searches this slice with a comparator function.
The comparator function should return an order code that indicates
whether its argument is Less
, Equal
or Greater
the desired
target.
If the slice is not sorted or if the comparator function does not
implement an order consistent with the sort order of the underlying
slice, the returned result is unspecified and meaningless.
If the value is found then Result::Ok
is returned, containing the
index of the matching element. If there are multiple matches, then any
one of the matches could be returned. The index is chosen
deterministically, but is subject to change in future versions of Rust.
If the value is not found then Result::Err
is returned, containing
the index where a matching element could be inserted while maintaining
sorted order.
See also binary_search
, binary_search_by_key
, and partition_point
.
§Examples
Looks up a series of four elements. The first is found, with a
uniquely determined position; the second and third are not
found; the fourth could match any position in [1, 4]
.
let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let seek = 13;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Ok(9));
let seek = 4;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(7));
let seek = 100;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(13));
let seek = 1;
let r = s.binary_search_by(|probe| probe.cmp(&seek));
assert!(match r { Ok(1..=4) => true, _ => false, });
Run1.10.0 · sourcepub fn binary_search_by_key<'a, B, F>(
&'a self,
b: &B,
f: F
) -> Result<usize, usize>
pub fn binary_search_by_key<'a, B, F>( &'a self, b: &B, f: F ) -> Result<usize, usize>
Binary searches this slice with a key extraction function.
Assumes that the slice is sorted by the key, for instance with
sort_by_key
using the same key extraction function.
If the slice is not sorted by the key, the returned result is
unspecified and meaningless.
If the value is found then Result::Ok
is returned, containing the
index of the matching element. If there are multiple matches, then any
one of the matches could be returned. The index is chosen
deterministically, but is subject to change in future versions of Rust.
If the value is not found then Result::Err
is returned, containing
the index where a matching element could be inserted while maintaining
sorted order.
See also binary_search
, binary_search_by
, and partition_point
.
§Examples
Looks up a series of four elements in a slice of pairs sorted by
their second elements. The first is found, with a uniquely
determined position; the second and third are not found; the
fourth could match any position in [1, 4]
.
let s = [(0, 0), (2, 1), (4, 1), (5, 1), (3, 1),
(1, 2), (2, 3), (4, 5), (5, 8), (3, 13),
(1, 21), (2, 34), (4, 55)];
assert_eq!(s.binary_search_by_key(&13, |&(a, b)| b), Ok(9));
assert_eq!(s.binary_search_by_key(&4, |&(a, b)| b), Err(7));
assert_eq!(s.binary_search_by_key(&100, |&(a, b)| b), Err(13));
let r = s.binary_search_by_key(&1, |&(a, b)| b);
assert!(match r { Ok(1..=4) => true, _ => false, });
Run1.20.0 · sourcepub fn sort_unstable(&mut self)where
T: Ord,
pub fn sort_unstable(&mut self)where
T: Ord,
Sorts the slice, but might not preserve the order of equal elements.
This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and O(n * log(n)) worst-case.
§Current implementation
The current algorithm is based on pattern-defeating quicksort by Orson Peters, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on slices with certain patterns. It uses some randomization to avoid degenerate cases, but with a fixed seed to always provide deterministic behavior.
It is typically faster than stable sorting, except in a few special cases, e.g., when the slice consists of several concatenated sorted sequences.
§Examples
let mut v = [-5, 4, 1, -3, 2];
v.sort_unstable();
assert!(v == [-5, -3, 1, 2, 4]);
Run1.20.0 · sourcepub fn sort_unstable_by<F>(&mut self, compare: F)
pub fn sort_unstable_by<F>(&mut self, compare: F)
Sorts the slice with a comparator function, but might not preserve the order of equal elements.
This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and O(n * log(n)) worst-case.
The comparator function must define a total ordering for the elements in the slice. If
the ordering is not total, the order of the elements is unspecified. An order is a
total order if it is (for all a
, b
and c
):
- total and antisymmetric: exactly one of
a < b
,a == b
ora > b
is true, and - transitive,
a < b
andb < c
impliesa < c
. The same must hold for both==
and>
.
For example, while f64
doesn’t implement Ord
because NaN != NaN
, we can use
partial_cmp
as our sort function when we know the slice doesn’t contain a NaN
.
let mut floats = [5f64, 4.0, 1.0, 3.0, 2.0];
floats.sort_unstable_by(|a, b| a.partial_cmp(b).unwrap());
assert_eq!(floats, [1.0, 2.0, 3.0, 4.0, 5.0]);
Run§Current implementation
The current algorithm is based on pattern-defeating quicksort by Orson Peters, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on slices with certain patterns. It uses some randomization to avoid degenerate cases, but with a fixed seed to always provide deterministic behavior.
It is typically faster than stable sorting, except in a few special cases, e.g., when the slice consists of several concatenated sorted sequences.
§Examples
let mut v = [5, 4, 1, 3, 2];
v.sort_unstable_by(|a, b| a.cmp(b));
assert!(v == [1, 2, 3, 4, 5]);
// reverse sorting
v.sort_unstable_by(|a, b| b.cmp(a));
assert!(v == [5, 4, 3, 2, 1]);
Run1.20.0 · sourcepub fn sort_unstable_by_key<K, F>(&mut self, f: F)
pub fn sort_unstable_by_key<K, F>(&mut self, f: F)
Sorts the slice with a key extraction function, but might not preserve the order of equal elements.
This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and O(m * n * log(n)) worst-case, where the key function is O(m).
§Current implementation
The current algorithm is based on pattern-defeating quicksort by Orson Peters, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on slices with certain patterns. It uses some randomization to avoid degenerate cases, but with a fixed seed to always provide deterministic behavior.
Due to its key calling strategy, sort_unstable_by_key
is likely to be slower than sort_by_cached_key
in
cases where the key function is expensive.
§Examples
let mut v = [-5i32, 4, 1, -3, 2];
v.sort_unstable_by_key(|k| k.abs());
assert!(v == [1, 2, -3, 4, -5]);
Run1.49.0 · sourcepub fn select_nth_unstable(
&mut self,
index: usize
) -> (&mut [T], &mut T, &mut [T])where
T: Ord,
pub fn select_nth_unstable(
&mut self,
index: usize
) -> (&mut [T], &mut T, &mut [T])where
T: Ord,
Reorder the slice such that the element at index
is at its final sorted position.
This reordering has the additional property that any value at position i < index
will be
less than or equal to any value at a position j > index
. Additionally, this reordering is
unstable (i.e. any number of equal elements may end up at position index
), in-place
(i.e. does not allocate), and runs in O(n) time.
This function is also known as “kth element” in other libraries.
It returns a triplet of the following from the reordered slice:
the subslice prior to index
, the element at index
, and the subslice after index
;
accordingly, the values in those two subslices will respectively all be less-than-or-equal-to
and greater-than-or-equal-to the value of the element at index
.
§Current implementation
The current algorithm is an introselect implementation based on Pattern Defeating Quicksort, which is also
the basis for sort_unstable
. The fallback algorithm is Median of Medians using Tukey’s Ninther for
pivot selection, which guarantees linear runtime for all inputs.
§Panics
Panics when index >= len()
, meaning it always panics on empty slices.
§Examples
let mut v = [-5i32, 4, 1, -3, 2];
// Find the median
v.select_nth_unstable(2);
// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
assert!(v == [-3, -5, 1, 2, 4] ||
v == [-5, -3, 1, 2, 4] ||
v == [-3, -5, 1, 4, 2] ||
v == [-5, -3, 1, 4, 2]);
Run1.49.0 · sourcepub fn select_nth_unstable_by<F>(
&mut self,
index: usize,
compare: F
) -> (&mut [T], &mut T, &mut [T])
pub fn select_nth_unstable_by<F>( &mut self, index: usize, compare: F ) -> (&mut [T], &mut T, &mut [T])
Reorder the slice with a comparator function such that the element at index
is at its
final sorted position.
This reordering has the additional property that any value at position i < index
will be
less than or equal to any value at a position j > index
using the comparator function.
Additionally, this reordering is unstable (i.e. any number of equal elements may end up at
position index
), in-place (i.e. does not allocate), and runs in O(n) time.
This function is also known as “kth element” in other libraries.
It returns a triplet of the following from
the slice reordered according to the provided comparator function: the subslice prior to
index
, the element at index
, and the subslice after index
; accordingly, the values in
those two subslices will respectively all be less-than-or-equal-to and greater-than-or-equal-to
the value of the element at index
.
§Current implementation
The current algorithm is an introselect implementation based on Pattern Defeating Quicksort, which is also
the basis for sort_unstable
. The fallback algorithm is Median of Medians using Tukey’s Ninther for
pivot selection, which guarantees linear runtime for all inputs.
§Panics
Panics when index >= len()
, meaning it always panics on empty slices.
§Examples
let mut v = [-5i32, 4, 1, -3, 2];
// Find the median as if the slice were sorted in descending order.
v.select_nth_unstable_by(2, |a, b| b.cmp(a));
// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
assert!(v == [2, 4, 1, -5, -3] ||
v == [2, 4, 1, -3, -5] ||
v == [4, 2, 1, -5, -3] ||
v == [4, 2, 1, -3, -5]);
Run1.49.0 · sourcepub fn select_nth_unstable_by_key<K, F>(
&mut self,
index: usize,
f: F
) -> (&mut [T], &mut T, &mut [T])
pub fn select_nth_unstable_by_key<K, F>( &mut self, index: usize, f: F ) -> (&mut [T], &mut T, &mut [T])
Reorder the slice with a key extraction function such that the element at index
is at its
final sorted position.
This reordering has the additional property that any value at position i < index
will be
less than or equal to any value at a position j > index
using the key extraction function.
Additionally, this reordering is unstable (i.e. any number of equal elements may end up at
position index
), in-place (i.e. does not allocate), and runs in O(n) time.
This function is also known as “kth element” in other libraries.
It returns a triplet of the following from
the slice reordered according to the provided key extraction function: the subslice prior to
index
, the element at index
, and the subslice after index
; accordingly, the values in
those two subslices will respectively all be less-than-or-equal-to and greater-than-or-equal-to
the value of the element at index
.
§Current implementation
The current algorithm is an introselect implementation based on Pattern Defeating Quicksort, which is also
the basis for sort_unstable
. The fallback algorithm is Median of Medians using Tukey’s Ninther for
pivot selection, which guarantees linear runtime for all inputs.
§Panics
Panics when index >= len()
, meaning it always panics on empty slices.
§Examples
let mut v = [-5i32, 4, 1, -3, 2];
// Return the median as if the array were sorted according to absolute value.
v.select_nth_unstable_by_key(2, |a| a.abs());
// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
assert!(v == [1, 2, -3, 4, -5] ||
v == [1, 2, -3, -5, 4] ||
v == [2, 1, -3, 4, -5] ||
v == [2, 1, -3, -5, 4]);
Runsourcepub fn partition_dedup(&mut self) -> (&mut [T], &mut [T])where
T: PartialEq,
🔬This is a nightly-only experimental API. (slice_partition_dedup
#54279)
pub fn partition_dedup(&mut self) -> (&mut [T], &mut [T])where
T: PartialEq,
slice_partition_dedup
#54279)Moves all consecutive repeated elements to the end of the slice according to the
PartialEq
trait implementation.
Returns two slices. The first contains no consecutive repeated elements. The second contains all the duplicates in no specified order.
If the slice is sorted, the first returned slice contains no duplicates.
§Examples
#![feature(slice_partition_dedup)]
let mut slice = [1, 2, 2, 3, 3, 2, 1, 1];
let (dedup, duplicates) = slice.partition_dedup();
assert_eq!(dedup, [1, 2, 3, 2, 1]);
assert_eq!(duplicates, [2, 3, 1]);
Runsourcepub fn partition_dedup_by<F>(&mut self, same_bucket: F) -> (&mut [T], &mut [T])
🔬This is a nightly-only experimental API. (slice_partition_dedup
#54279)
pub fn partition_dedup_by<F>(&mut self, same_bucket: F) -> (&mut [T], &mut [T])
slice_partition_dedup
#54279)Moves all but the first of consecutive elements to the end of the slice satisfying a given equality relation.
Returns two slices. The first contains no consecutive repeated elements. The second contains all the duplicates in no specified order.
The same_bucket
function is passed references to two elements from the slice and
must determine if the elements compare equal. The elements are passed in opposite order
from their order in the slice, so if same_bucket(a, b)
returns true
, a
is moved
at the end of the slice.
If the slice is sorted, the first returned slice contains no duplicates.
§Examples
#![feature(slice_partition_dedup)]
let mut slice = ["foo", "Foo", "BAZ", "Bar", "bar", "baz", "BAZ"];
let (dedup, duplicates) = slice.partition_dedup_by(|a, b| a.eq_ignore_ascii_case(b));
assert_eq!(dedup, ["foo", "BAZ", "Bar", "baz"]);
assert_eq!(duplicates, ["bar", "Foo", "BAZ"]);
Runsourcepub fn partition_dedup_by_key<K, F>(&mut self, key: F) -> (&mut [T], &mut [T])
🔬This is a nightly-only experimental API. (slice_partition_dedup
#54279)
pub fn partition_dedup_by_key<K, F>(&mut self, key: F) -> (&mut [T], &mut [T])
slice_partition_dedup
#54279)Moves all but the first of consecutive elements to the end of the slice that resolve to the same key.
Returns two slices. The first contains no consecutive repeated elements. The second contains all the duplicates in no specified order.
If the slice is sorted, the first returned slice contains no duplicates.
§Examples
#![feature(slice_partition_dedup)]
let mut slice = [10, 20, 21, 30, 30, 20, 11, 13];
let (dedup, duplicates) = slice.partition_dedup_by_key(|i| *i / 10);
assert_eq!(dedup, [10, 20, 30, 20, 11]);
assert_eq!(duplicates, [21, 30, 13]);
Run1.26.0 · sourcepub fn rotate_left(&mut self, mid: usize)
pub fn rotate_left(&mut self, mid: usize)
Rotates the slice in-place such that the first mid
elements of the
slice move to the end while the last self.len() - mid
elements move to
the front. After calling rotate_left
, the element previously at index
mid
will become the first element in the slice.
§Panics
This function will panic if mid
is greater than the length of the
slice. Note that mid == self.len()
does not panic and is a no-op
rotation.
§Complexity
Takes linear (in self.len()
) time.
§Examples
let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a.rotate_left(2);
assert_eq!(a, ['c', 'd', 'e', 'f', 'a', 'b']);
RunRotating a subslice:
let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a[1..5].rotate_left(1);
assert_eq!(a, ['a', 'c', 'd', 'e', 'b', 'f']);
Run1.26.0 · sourcepub fn rotate_right(&mut self, k: usize)
pub fn rotate_right(&mut self, k: usize)
Rotates the slice in-place such that the first self.len() - k
elements of the slice move to the end while the last k
elements move
to the front. After calling rotate_right
, the element previously at
index self.len() - k
will become the first element in the slice.
§Panics
This function will panic if k
is greater than the length of the
slice. Note that k == self.len()
does not panic and is a no-op
rotation.
§Complexity
Takes linear (in self.len()
) time.
§Examples
let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a.rotate_right(2);
assert_eq!(a, ['e', 'f', 'a', 'b', 'c', 'd']);
RunRotating a subslice:
let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a[1..5].rotate_right(1);
assert_eq!(a, ['a', 'e', 'b', 'c', 'd', 'f']);
Run1.51.0 · sourcepub fn fill_with<F>(&mut self, f: F)where
F: FnMut() -> T,
pub fn fill_with<F>(&mut self, f: F)where
F: FnMut() -> T,
Fills self
with elements returned by calling a closure repeatedly.
This method uses a closure to create new values. If you’d rather
Clone
a given value, use fill
. If you want to use the Default
trait to generate values, you can pass Default::default
as the
argument.
§Examples
let mut buf = vec![1; 10];
buf.fill_with(Default::default);
assert_eq!(buf, vec![0; 10]);
Run1.7.0 · sourcepub fn clone_from_slice(&mut self, src: &[T])where
T: Clone,
pub fn clone_from_slice(&mut self, src: &[T])where
T: Clone,
Copies the elements from src
into self
.
The length of src
must be the same as self
.
§Panics
This function will panic if the two slices have different lengths.
§Examples
Cloning two elements from a slice into another:
let src = [1, 2, 3, 4];
let mut dst = [0, 0];
// Because the slices have to be the same length,
// we slice the source slice from four elements
// to two. It will panic if we don't do this.
dst.clone_from_slice(&src[2..]);
assert_eq!(src, [1, 2, 3, 4]);
assert_eq!(dst, [3, 4]);
RunRust enforces that there can only be one mutable reference with no
immutable references to a particular piece of data in a particular
scope. Because of this, attempting to use clone_from_slice
on a
single slice will result in a compile failure:
To work around this, we can use split_at_mut
to create two distinct
sub-slices from a slice:
let mut slice = [1, 2, 3, 4, 5];
{
let (left, right) = slice.split_at_mut(2);
left.clone_from_slice(&right[1..]);
}
assert_eq!(slice, [4, 5, 3, 4, 5]);
Run1.9.0 · sourcepub fn copy_from_slice(&mut self, src: &[T])where
T: Copy,
pub fn copy_from_slice(&mut self, src: &[T])where
T: Copy,
Copies all elements from src
into self
, using a memcpy.
The length of src
must be the same as self
.
If T
does not implement Copy
, use clone_from_slice
.
§Panics
This function will panic if the two slices have different lengths.
§Examples
Copying two elements from a slice into another:
let src = [1, 2, 3, 4];
let mut dst = [0, 0];
// Because the slices have to be the same length,
// we slice the source slice from four elements
// to two. It will panic if we don't do this.
dst.copy_from_slice(&src[2..]);
assert_eq!(src, [1, 2, 3, 4]);
assert_eq!(dst, [3, 4]);
RunRust enforces that there can only be one mutable reference with no
immutable references to a particular piece of data in a particular
scope. Because of this, attempting to use copy_from_slice
on a
single slice will result in a compile failure:
To work around this, we can use split_at_mut
to create two distinct
sub-slices from a slice:
let mut slice = [1, 2, 3, 4, 5];
{
let (left, right) = slice.split_at_mut(2);
left.copy_from_slice(&right[1..]);
}
assert_eq!(slice, [4, 5, 3, 4, 5]);
Run1.37.0 · sourcepub fn copy_within<R>(&mut self, src: R, dest: usize)
pub fn copy_within<R>(&mut self, src: R, dest: usize)
Copies elements from one part of the slice to another part of itself, using a memmove.
src
is the range within self
to copy from. dest
is the starting
index of the range within self
to copy to, which will have the same
length as src
. The two ranges may overlap. The ends of the two ranges
must be less than or equal to self.len()
.
§Panics
This function will panic if either range exceeds the end of the slice,
or if the end of src
is before the start.
§Examples
Copying four bytes within a slice:
let mut bytes = *b"Hello, World!";
bytes.copy_within(1..5, 8);
assert_eq!(&bytes, b"Hello, Wello!");
Run1.27.0 · sourcepub fn swap_with_slice(&mut self, other: &mut [T])
pub fn swap_with_slice(&mut self, other: &mut [T])
Swaps all elements in self
with those in other
.
The length of other
must be the same as self
.
§Panics
This function will panic if the two slices have different lengths.
§Example
Swapping two elements across slices:
let mut slice1 = [0, 0];
let mut slice2 = [1, 2, 3, 4];
slice1.swap_with_slice(&mut slice2[2..]);
assert_eq!(slice1, [3, 4]);
assert_eq!(slice2, [1, 2, 0, 0]);
RunRust enforces that there can only be one mutable reference to a
particular piece of data in a particular scope. Because of this,
attempting to use swap_with_slice
on a single slice will result in
a compile failure:
To work around this, we can use split_at_mut
to create two distinct
mutable sub-slices from a slice:
let mut slice = [1, 2, 3, 4, 5];
{
let (left, right) = slice.split_at_mut(2);
left.swap_with_slice(&mut right[1..]);
}
assert_eq!(slice, [4, 5, 3, 1, 2]);
Run1.30.0 · sourcepub unsafe fn align_to<U>(&self) -> (&[T], &[U], &[T])
pub unsafe fn align_to<U>(&self) -> (&[T], &[U], &[T])
Transmute the slice to a slice of another type, ensuring alignment of the types is maintained.
This method splits the slice into three distinct slices: prefix, correctly aligned middle slice of a new type, and the suffix slice. How exactly the slice is split up is not specified; the middle part may be smaller than necessary. However, if this fails to return a maximal middle part, that is because code is running in a context where performance does not matter, such as a sanitizer attempting to find alignment bugs. Regular code running in a default (debug or release) execution will return a maximal middle part.
This method has no purpose when either input element T
or output element U
are
zero-sized and will return the original slice without splitting anything.
§Safety
This method is essentially a transmute
with respect to the elements in the returned
middle slice, so all the usual caveats pertaining to transmute::<T, U>
also apply here.
§Examples
Basic usage:
unsafe {
let bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
let (prefix, shorts, suffix) = bytes.align_to::<u16>();
// less_efficient_algorithm_for_bytes(prefix);
// more_efficient_algorithm_for_aligned_shorts(shorts);
// less_efficient_algorithm_for_bytes(suffix);
}
Run1.30.0 · sourcepub unsafe fn align_to_mut<U>(&mut self) -> (&mut [T], &mut [U], &mut [T])
pub unsafe fn align_to_mut<U>(&mut self) -> (&mut [T], &mut [U], &mut [T])
Transmute the mutable slice to a mutable slice of another type, ensuring alignment of the types is maintained.
This method splits the slice into three distinct slices: prefix, correctly aligned middle slice of a new type, and the suffix slice. How exactly the slice is split up is not specified; the middle part may be smaller than necessary. However, if this fails to return a maximal middle part, that is because code is running in a context where performance does not matter, such as a sanitizer attempting to find alignment bugs. Regular code running in a default (debug or release) execution will return a maximal middle part.
This method has no purpose when either input element T
or output element U
are
zero-sized and will return the original slice without splitting anything.
§Safety
This method is essentially a transmute
with respect to the elements in the returned
middle slice, so all the usual caveats pertaining to transmute::<T, U>
also apply here.
§Examples
Basic usage:
unsafe {
let mut bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
let (prefix, shorts, suffix) = bytes.align_to_mut::<u16>();
// less_efficient_algorithm_for_bytes(prefix);
// more_efficient_algorithm_for_aligned_shorts(shorts);
// less_efficient_algorithm_for_bytes(suffix);
}
Runsourcepub fn as_simd<const LANES: usize>(&self) -> (&[T], &[Simd<T, LANES>], &[T])
🔬This is a nightly-only experimental API. (portable_simd
#86656)
pub fn as_simd<const LANES: usize>(&self) -> (&[T], &[Simd<T, LANES>], &[T])
portable_simd
#86656)Split a slice into a prefix, a middle of aligned SIMD types, and a suffix.
This is a safe wrapper around slice::align_to
, so has the same weak
postconditions as that method. You’re only assured that
self.len() == prefix.len() + middle.len() * LANES + suffix.len()
.
Notably, all of the following are possible:
prefix.len() >= LANES
.middle.is_empty()
despiteself.len() >= 3 * LANES
.suffix.len() >= LANES
.
That said, this is a safe method, so if you’re only writing safe code, then this can at most cause incorrect logic, not unsoundness.
§Panics
This will panic if the size of the SIMD type is different from
LANES
times that of the scalar.
At the time of writing, the trait restrictions on Simd<T, LANES>
keeps
that from ever happening, as only power-of-two numbers of lanes are
supported. It’s possible that, in the future, those restrictions might
be lifted in a way that would make it possible to see panics from this
method for something like LANES == 3
.
§Examples
#![feature(portable_simd)]
use core::simd::prelude::*;
let short = &[1, 2, 3];
let (prefix, middle, suffix) = short.as_simd::<4>();
assert_eq!(middle, []); // Not enough elements for anything in the middle
// They might be split in any possible way between prefix and suffix
let it = prefix.iter().chain(suffix).copied();
assert_eq!(it.collect::<Vec<_>>(), vec![1, 2, 3]);
fn basic_simd_sum(x: &[f32]) -> f32 {
use std::ops::Add;
let (prefix, middle, suffix) = x.as_simd();
let sums = f32x4::from_array([
prefix.iter().copied().sum(),
0.0,
0.0,
suffix.iter().copied().sum(),
]);
let sums = middle.iter().copied().fold(sums, f32x4::add);
sums.reduce_sum()
}
let numbers: Vec<f32> = (1..101).map(|x| x as _).collect();
assert_eq!(basic_simd_sum(&numbers[1..99]), 4949.0);
Runsourcepub fn as_simd_mut<const LANES: usize>(
&mut self
) -> (&mut [T], &mut [Simd<T, LANES>], &mut [T])
🔬This is a nightly-only experimental API. (portable_simd
#86656)
pub fn as_simd_mut<const LANES: usize>( &mut self ) -> (&mut [T], &mut [Simd<T, LANES>], &mut [T])
portable_simd
#86656)Split a mutable slice into a mutable prefix, a middle of aligned SIMD types, and a mutable suffix.
This is a safe wrapper around slice::align_to_mut
, so has the same weak
postconditions as that method. You’re only assured that
self.len() == prefix.len() + middle.len() * LANES + suffix.len()
.
Notably, all of the following are possible:
prefix.len() >= LANES
.middle.is_empty()
despiteself.len() >= 3 * LANES
.suffix.len() >= LANES
.
That said, this is a safe method, so if you’re only writing safe code, then this can at most cause incorrect logic, not unsoundness.
This is the mutable version of slice::as_simd
; see that for examples.
§Panics
This will panic if the size of the SIMD type is different from
LANES
times that of the scalar.
At the time of writing, the trait restrictions on Simd<T, LANES>
keeps
that from ever happening, as only power-of-two numbers of lanes are
supported. It’s possible that, in the future, those restrictions might
be lifted in a way that would make it possible to see panics from this
method for something like LANES == 3
.
sourcepub fn is_sorted(&self) -> boolwhere
T: PartialOrd,
🔬This is a nightly-only experimental API. (is_sorted
#53485)
pub fn is_sorted(&self) -> boolwhere
T: PartialOrd,
is_sorted
#53485)Checks if the elements of this slice are sorted.
That is, for each element a
and its following element b
, a <= b
must hold. If the
slice yields exactly zero or one element, true
is returned.
Note that if Self::Item
is only PartialOrd
, but not Ord
, the above definition
implies that this function returns false
if any two consecutive items are not
comparable.
§Examples
#![feature(is_sorted)]
let empty: [i32; 0] = [];
assert!([1, 2, 2, 9].is_sorted());
assert!(![1, 3, 2, 4].is_sorted());
assert!([0].is_sorted());
assert!(empty.is_sorted());
assert!(![0.0, 1.0, f32::NAN].is_sorted());
Runsourcepub fn is_sorted_by<'a, F>(&'a self, compare: F) -> bool
🔬This is a nightly-only experimental API. (is_sorted
#53485)
pub fn is_sorted_by<'a, F>(&'a self, compare: F) -> bool
is_sorted
#53485)Checks if the elements of this slice are sorted using the given comparator function.
Instead of using PartialOrd::partial_cmp
, this function uses the given compare
function to determine whether two elements are to be considered in sorted order.
§Examples
#![feature(is_sorted)]
assert!([1, 2, 2, 9].is_sorted_by(|a, b| a <= b));
assert!(![1, 2, 2, 9].is_sorted_by(|a, b| a < b));
assert!([0].is_sorted_by(|a, b| true));
assert!([0].is_sorted_by(|a, b| false));
let empty: [i32; 0] = [];
assert!(empty.is_sorted_by(|a, b| false));
assert!(empty.is_sorted_by(|a, b| true));
Runsourcepub fn is_sorted_by_key<'a, F, K>(&'a self, f: F) -> bool
🔬This is a nightly-only experimental API. (is_sorted
#53485)
pub fn is_sorted_by_key<'a, F, K>(&'a self, f: F) -> bool
is_sorted
#53485)Checks if the elements of this slice are sorted using the given key extraction function.
Instead of comparing the slice’s elements directly, this function compares the keys of the
elements, as determined by f
. Apart from that, it’s equivalent to is_sorted
; see its
documentation for more information.
§Examples
#![feature(is_sorted)]
assert!(["c", "bb", "aaa"].is_sorted_by_key(|s| s.len()));
assert!(![-2i32, -1, 0, 3].is_sorted_by_key(|n| n.abs()));
Run1.52.0 · sourcepub fn partition_point<P>(&self, pred: P) -> usize
pub fn partition_point<P>(&self, pred: P) -> usize
Returns the index of the partition point according to the given predicate (the index of the first element of the second partition).
The slice is assumed to be partitioned according to the given predicate.
This means that all elements for which the predicate returns true are at the start of the slice
and all elements for which the predicate returns false are at the end.
For example, [7, 15, 3, 5, 4, 12, 6]
is partitioned under the predicate x % 2 != 0
(all odd numbers are at the start, all even at the end).
If this slice is not partitioned, the returned result is unspecified and meaningless, as this method performs a kind of binary search.
See also binary_search
, binary_search_by
, and binary_search_by_key
.
§Examples
let v = [1, 2, 3, 3, 5, 6, 7];
let i = v.partition_point(|&x| x < 5);
assert_eq!(i, 4);
assert!(v[..i].iter().all(|&x| x < 5));
assert!(v[i..].iter().all(|&x| !(x < 5)));
RunIf all elements of the slice match the predicate, including if the slice is empty, then the length of the slice will be returned:
let a = [2, 4, 8];
assert_eq!(a.partition_point(|x| x < &100), a.len());
let a: [i32; 0] = [];
assert_eq!(a.partition_point(|x| x < &100), 0);
RunIf you want to insert an item to a sorted vector, while maintaining sort order:
let mut s = vec![0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let num = 42;
let idx = s.partition_point(|&x| x < num);
s.insert(idx, num);
assert_eq!(s, [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 42, 55]);
Runsourcepub fn take<R, 'a>(self: &mut &'a [T], range: R) -> Option<&'a [T]>where
R: OneSidedRange<usize>,
🔬This is a nightly-only experimental API. (slice_take
#62280)
pub fn take<R, 'a>(self: &mut &'a [T], range: R) -> Option<&'a [T]>where
R: OneSidedRange<usize>,
slice_take
#62280)Removes the subslice corresponding to the given range and returns a reference to it.
Returns None
and does not modify the slice if the given
range is out of bounds.
Note that this method only accepts one-sided ranges such as
2..
or ..6
, but not 2..6
.
§Examples
Taking the first three elements of a slice:
#![feature(slice_take)]
let mut slice: &[_] = &['a', 'b', 'c', 'd'];
let mut first_three = slice.take(..3).unwrap();
assert_eq!(slice, &['d']);
assert_eq!(first_three, &['a', 'b', 'c']);
RunTaking the last two elements of a slice:
#![feature(slice_take)]
let mut slice: &[_] = &['a', 'b', 'c', 'd'];
let mut tail = slice.take(2..).unwrap();
assert_eq!(slice, &['a', 'b']);
assert_eq!(tail, &['c', 'd']);
RunGetting None
when range
is out of bounds:
#![feature(slice_take)]
let mut slice: &[_] = &['a', 'b', 'c', 'd'];
assert_eq!(None, slice.take(5..));
assert_eq!(None, slice.take(..5));
assert_eq!(None, slice.take(..=4));
let expected: &[char] = &['a', 'b', 'c', 'd'];
assert_eq!(Some(expected), slice.take(..4));
Runsourcepub fn take_mut<R, 'a>(self: &mut &'a mut [T], range: R) -> Option<&'a mut [T]>where
R: OneSidedRange<usize>,
🔬This is a nightly-only experimental API. (slice_take
#62280)
pub fn take_mut<R, 'a>(self: &mut &'a mut [T], range: R) -> Option<&'a mut [T]>where
R: OneSidedRange<usize>,
slice_take
#62280)Removes the subslice corresponding to the given range and returns a mutable reference to it.
Returns None
and does not modify the slice if the given
range is out of bounds.
Note that this method only accepts one-sided ranges such as
2..
or ..6
, but not 2..6
.
§Examples
Taking the first three elements of a slice:
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c', 'd'];
let mut first_three = slice.take_mut(..3).unwrap();
assert_eq!(slice, &mut ['d']);
assert_eq!(first_three, &mut ['a', 'b', 'c']);
RunTaking the last two elements of a slice:
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c', 'd'];
let mut tail = slice.take_mut(2..).unwrap();
assert_eq!(slice, &mut ['a', 'b']);
assert_eq!(tail, &mut ['c', 'd']);
RunGetting None
when range
is out of bounds:
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c', 'd'];
assert_eq!(None, slice.take_mut(5..));
assert_eq!(None, slice.take_mut(..5));
assert_eq!(None, slice.take_mut(..=4));
let expected: &mut [_] = &mut ['a', 'b', 'c', 'd'];
assert_eq!(Some(expected), slice.take_mut(..4));
Runsourcepub fn take_first<'a>(self: &mut &'a [T]) -> Option<&'a T>
🔬This is a nightly-only experimental API. (slice_take
#62280)
pub fn take_first<'a>(self: &mut &'a [T]) -> Option<&'a T>
slice_take
#62280)sourcepub fn take_first_mut<'a>(self: &mut &'a mut [T]) -> Option<&'a mut T>
🔬This is a nightly-only experimental API. (slice_take
#62280)
pub fn take_first_mut<'a>(self: &mut &'a mut [T]) -> Option<&'a mut T>
slice_take
#62280)Removes the first element of the slice and returns a mutable reference to it.
Returns None
if the slice is empty.
§Examples
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c'];
let first = slice.take_first_mut().unwrap();
*first = 'd';
assert_eq!(slice, &['b', 'c']);
assert_eq!(first, &'d');
Runsourcepub fn take_last<'a>(self: &mut &'a [T]) -> Option<&'a T>
🔬This is a nightly-only experimental API. (slice_take
#62280)
pub fn take_last<'a>(self: &mut &'a [T]) -> Option<&'a T>
slice_take
#62280)sourcepub fn take_last_mut<'a>(self: &mut &'a mut [T]) -> Option<&'a mut T>
🔬This is a nightly-only experimental API. (slice_take
#62280)
pub fn take_last_mut<'a>(self: &mut &'a mut [T]) -> Option<&'a mut T>
slice_take
#62280)Removes the last element of the slice and returns a mutable reference to it.
Returns None
if the slice is empty.
§Examples
#![feature(slice_take)]
let mut slice: &mut [_] = &mut ['a', 'b', 'c'];
let last = slice.take_last_mut().unwrap();
*last = 'd';
assert_eq!(slice, &['a', 'b']);
assert_eq!(last, &'d');
Runsourcepub unsafe fn get_many_unchecked_mut<const N: usize>(
&mut self,
indices: [usize; N]
) -> [&mut T; N]
🔬This is a nightly-only experimental API. (get_many_mut
#104642)
pub unsafe fn get_many_unchecked_mut<const N: usize>( &mut self, indices: [usize; N] ) -> [&mut T; N]
get_many_mut
#104642)Returns mutable references to many indices at once, without doing any checks.
For a safe alternative see get_many_mut
.
§Safety
Calling this method with overlapping or out-of-bounds indices is undefined behavior even if the resulting references are not used.
§Examples
#![feature(get_many_mut)]
let x = &mut [1, 2, 4];
unsafe {
let [a, b] = x.get_many_unchecked_mut([0, 2]);
*a *= 10;
*b *= 100;
}
assert_eq!(x, &[10, 2, 400]);
Runsourcepub fn get_many_mut<const N: usize>(
&mut self,
indices: [usize; N]
) -> Result<[&mut T; N], GetManyMutError<N>>
🔬This is a nightly-only experimental API. (get_many_mut
#104642)
pub fn get_many_mut<const N: usize>( &mut self, indices: [usize; N] ) -> Result<[&mut T; N], GetManyMutError<N>>
get_many_mut
#104642)Returns mutable references to many indices at once.
Returns an error if any index is out-of-bounds, or if the same index was passed more than once.
§Examples
#![feature(get_many_mut)]
let v = &mut [1, 2, 3];
if let Ok([a, b]) = v.get_many_mut([0, 2]) {
*a = 413;
*b = 612;
}
assert_eq!(v, &[413, 2, 612]);
Runsource§impl [f64]
impl [f64]
sourcepub fn sort_floats(&mut self)
🔬This is a nightly-only experimental API. (sort_floats
#93396)
pub fn sort_floats(&mut self)
sort_floats
#93396)Sorts the slice of floats.
This sort is in-place (i.e. does not allocate), O(n * log(n)) worst-case, and uses
the ordering defined by f64::total_cmp
.
§Current implementation
This uses the same sorting algorithm as sort_unstable_by
.
§Examples
#![feature(sort_floats)]
let mut v = [2.6, -5e-8, f64::NAN, 8.29, f64::INFINITY, -1.0, 0.0, -f64::INFINITY, -0.0];
v.sort_floats();
let sorted = [-f64::INFINITY, -1.0, -5e-8, -0.0, 0.0, 2.6, 8.29, f64::INFINITY, f64::NAN];
assert_eq!(&v[..8], &sorted[..8]);
assert!(v[8].is_nan());
Runsource§impl [AsciiChar]
impl [AsciiChar]
source§impl<T> [T]
impl<T> [T]
sourcepub fn sort(&mut self)where
T: Ord,
pub fn sort(&mut self)where
T: Ord,
Sorts the slice.
This sort is stable (i.e., does not reorder equal elements) and O(n * log(n)) worst-case.
When applicable, unstable sorting is preferred because it is generally faster than stable
sorting and it doesn’t allocate auxiliary memory.
See sort_unstable
.
§Current implementation
The current algorithm is an adaptive, iterative merge sort inspired by timsort. It is designed to be very fast in cases where the slice is nearly sorted, or consists of two or more sorted sequences concatenated one after another.
Also, it allocates temporary storage half the size of self
, but for short slices a
non-allocating insertion sort is used instead.
§Examples
let mut v = [-5, 4, 1, -3, 2];
v.sort();
assert!(v == [-5, -3, 1, 2, 4]);
Runsourcepub fn sort_by<F>(&mut self, compare: F)
pub fn sort_by<F>(&mut self, compare: F)
Sorts the slice with a comparator function.
This sort is stable (i.e., does not reorder equal elements) and O(n * log(n)) worst-case.
The comparator function must define a total ordering for the elements in the slice. If
the ordering is not total, the order of the elements is unspecified. An order is a
total order if it is (for all a
, b
and c
):
- total and antisymmetric: exactly one of
a < b
,a == b
ora > b
is true, and - transitive,
a < b
andb < c
impliesa < c
. The same must hold for both==
and>
.
For example, while f64
doesn’t implement Ord
because NaN != NaN
, we can use
partial_cmp
as our sort function when we know the slice doesn’t contain a NaN
.
let mut floats = [5f64, 4.0, 1.0, 3.0, 2.0];
floats.sort_by(|a, b| a.partial_cmp(b).unwrap());
assert_eq!(floats, [1.0, 2.0, 3.0, 4.0, 5.0]);
RunWhen applicable, unstable sorting is preferred because it is generally faster than stable
sorting and it doesn’t allocate auxiliary memory.
See sort_unstable_by
.
§Current implementation
The current algorithm is an adaptive, iterative merge sort inspired by timsort. It is designed to be very fast in cases where the slice is nearly sorted, or consists of two or more sorted sequences concatenated one after another.
Also, it allocates temporary storage half the size of self
, but for short slices a
non-allocating insertion sort is used instead.
§Examples
let mut v = [5, 4, 1, 3, 2];
v.sort_by(|a, b| a.cmp(b));
assert!(v == [1, 2, 3, 4, 5]);
// reverse sorting
v.sort_by(|a, b| b.cmp(a));
assert!(v == [5, 4, 3, 2, 1]);
Run1.7.0 · sourcepub fn sort_by_key<K, F>(&mut self, f: F)
pub fn sort_by_key<K, F>(&mut self, f: F)
Sorts the slice with a key extraction function.
This sort is stable (i.e., does not reorder equal elements) and O(m * n * log(n)) worst-case, where the key function is O(m).
For expensive key functions (e.g. functions that are not simple property accesses or
basic operations), sort_by_cached_key
is likely to be
significantly faster, as it does not recompute element keys.
When applicable, unstable sorting is preferred because it is generally faster than stable
sorting and it doesn’t allocate auxiliary memory.
See sort_unstable_by_key
.
§Current implementation
The current algorithm is an adaptive, iterative merge sort inspired by timsort. It is designed to be very fast in cases where the slice is nearly sorted, or consists of two or more sorted sequences concatenated one after another.
Also, it allocates temporary storage half the size of self
, but for short slices a
non-allocating insertion sort is used instead.
§Examples
let mut v = [-5i32, 4, 1, -3, 2];
v.sort_by_key(|k| k.abs());
assert!(v == [1, 2, -3, 4, -5]);
Run1.34.0 · sourcepub fn sort_by_cached_key<K, F>(&mut self, f: F)
pub fn sort_by_cached_key<K, F>(&mut self, f: F)
Sorts the slice with a key extraction function.
During sorting, the key function is called at most once per element, by using temporary storage to remember the results of key evaluation. The order of calls to the key function is unspecified and may change in future versions of the standard library.
This sort is stable (i.e., does not reorder equal elements) and O(m * n + n * log(n)) worst-case, where the key function is O(m).
For simple key functions (e.g., functions that are property accesses or
basic operations), sort_by_key
is likely to be
faster.
§Current implementation
The current algorithm is based on pattern-defeating quicksort by Orson Peters, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on slices with certain patterns. It uses some randomization to avoid degenerate cases, but with a fixed seed to always provide deterministic behavior.
In the worst case, the algorithm allocates temporary storage in a Vec<(K, usize)>
the
length of the slice.
§Examples
let mut v = [-5i32, 4, 32, -3, 2];
v.sort_by_cached_key(|k| k.to_string());
assert!(v == [-3, -5, 2, 32, 4]);
Runsourcepub fn to_vec_in<A>(&self, alloc: A) -> Vec<T, A>
🔬This is a nightly-only experimental API. (allocator_api
#32838)
pub fn to_vec_in<A>(&self, alloc: A) -> Vec<T, A>
allocator_api
#32838)sourcepub fn into_vec<A>(self: Box<[T], A>) -> Vec<T, A>where
A: Allocator,
pub fn into_vec<A>(self: Box<[T], A>) -> Vec<T, A>where
A: Allocator,
Converts self
into a vector without clones or allocation.
The resulting vector can be converted back into a box via
Vec<T>
’s into_boxed_slice
method.
§Examples
let s: Box<[i32]> = Box::new([10, 40, 30]);
let x = s.into_vec();
// `s` cannot be used anymore because it has been converted into `x`.
assert_eq!(x, vec![10, 40, 30]);
Runsource§impl [u8]
impl [u8]
1.23.0 · sourcepub fn to_ascii_uppercase(&self) -> Vec<u8> ⓘ
pub fn to_ascii_uppercase(&self) -> Vec<u8> ⓘ
Returns a vector containing a copy of this slice where each byte is mapped to its ASCII upper case equivalent.
ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.
To uppercase the value in-place, use make_ascii_uppercase
.
1.23.0 · sourcepub fn to_ascii_lowercase(&self) -> Vec<u8> ⓘ
pub fn to_ascii_lowercase(&self) -> Vec<u8> ⓘ
Returns a vector containing a copy of this slice where each byte is mapped to its ASCII lower case equivalent.
ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.
To lowercase the value in-place, use make_ascii_lowercase
.
Trait Implementations§
source§impl AsciiExt for [u8]
impl AsciiExt for [u8]
§type Owned = Vec<u8>
type Owned = Vec<u8>
source§fn is_ascii(&self) -> bool
fn is_ascii(&self) -> bool
source§fn to_ascii_uppercase(&self) -> Self::Owned
fn to_ascii_uppercase(&self) -> Self::Owned
source§fn to_ascii_lowercase(&self) -> Self::Owned
fn to_ascii_lowercase(&self) -> Self::Owned
source§fn eq_ignore_ascii_case(&self, o: &Self) -> bool
fn eq_ignore_ascii_case(&self, o: &Self) -> bool
source§fn make_ascii_uppercase(&mut self)
fn make_ascii_uppercase(&mut self)
source§fn make_ascii_lowercase(&mut self)
fn make_ascii_lowercase(&mut self)
1.4.0 · source§impl<T, const N: usize> BorrowMut<[T]> for [T; N]
impl<T, const N: usize> BorrowMut<[T]> for [T; N]
source§fn borrow_mut(&mut self) -> &mut [T]
fn borrow_mut(&mut self) -> &mut [T]
source§impl<T, A> BorrowMut<[T]> for Vec<T, A>where
A: Allocator,
impl<T, A> BorrowMut<[T]> for Vec<T, A>where
A: Allocator,
source§fn borrow_mut(&mut self) -> &mut [T]
fn borrow_mut(&mut self) -> &mut [T]
source§impl BufRead for &[u8]
impl BufRead for &[u8]
source§fn fill_buf(&mut self) -> Result<&[u8]>
fn fill_buf(&mut self) -> Result<&[u8]>
source§fn consume(&mut self, amt: usize)
fn consume(&mut self, amt: usize)
amt
bytes have been consumed from the buffer,
so they should no longer be returned in calls to read
. Read moresource§fn has_data_left(&mut self) -> Result<bool>
fn has_data_left(&mut self) -> Result<bool>
buf_read_has_data_left
#86423)Read
has any data left to be read. Read moresource§fn skip_until(&mut self, byte: u8) -> Result<usize>
fn skip_until(&mut self, byte: u8) -> Result<usize>
bufread_skip_until
#111735)byte
or EOF is reached. Read moresource§fn read_line(&mut self, buf: &mut String) -> Result<usize>
fn read_line(&mut self, buf: &mut String) -> Result<usize>
0xA
byte) is reached, and append
them to the provided String
buffer. Read moresource§impl<S> Concat<str> for [S]
impl<S> Concat<str> for [S]
Note: str
in Concat<str>
is not meaningful here.
This type parameter of the trait only exists to enable another impl.
1.17.0 · source§impl<T> From<&[T]> for Box<[T]>where
T: Clone,
impl<T> From<&[T]> for Box<[T]>where
T: Clone,
source§fn from(slice: &[T]) -> Box<[T]>
fn from(slice: &[T]) -> Box<[T]>
Converts a &[T]
into a Box<[T]>
This conversion allocates on the heap
and performs a copy of slice
and its contents.
§Examples
// create a &[u8] which will be used to create a Box<[u8]>
let slice: &[u8] = &[104, 101, 108, 108, 111];
let boxed_slice: Box<[u8]> = Box::from(slice);
println!("{boxed_slice:?}");
Runsource§impl<'data> From<&'data mut [MaybeUninit<u8>]> for BorrowedBuf<'data>
impl<'data> From<&'data mut [MaybeUninit<u8>]> for BorrowedBuf<'data>
Create a new BorrowedBuf
from an uninitialized buffer.
Use set_init
if part of the buffer is known to be already initialized.
source§fn from(buf: &'data mut [MaybeUninit<u8>]) -> BorrowedBuf<'data>
fn from(buf: &'data mut [MaybeUninit<u8>]) -> BorrowedBuf<'data>
source§impl<'data> From<&'data mut [u8]> for BorrowedBuf<'data>
impl<'data> From<&'data mut [u8]> for BorrowedBuf<'data>
Create a new BorrowedBuf
from a fully initialized slice.
source§fn from(slice: &'data mut [u8]) -> BorrowedBuf<'data>
fn from(slice: &'data mut [u8]) -> BorrowedBuf<'data>
1.19.0 · source§impl<A> From<Box<str, A>> for Box<[u8], A>where
A: Allocator,
impl<A> From<Box<str, A>> for Box<[u8], A>where
A: Allocator,
source§fn from(s: Box<str, A>) -> Box<[u8], A>
fn from(s: Box<str, A>) -> Box<[u8], A>
Converts a Box<str>
into a Box<[u8]>
This conversion does not allocate on the heap and happens in place.
§Examples
// create a Box<str> which will be used to create a Box<[u8]>
let boxed: Box<str> = Box::from("hello");
let boxed_str: Box<[u8]> = Box::from(boxed);
// create a &[u8] which will be used to create a Box<[u8]>
let slice: &[u8] = &[104, 101, 108, 108, 111];
let boxed_slice = Box::from(slice);
assert_eq!(boxed_slice, boxed_str);
Run1.20.0 · source§impl<T, A> From<Vec<T, A>> for Box<[T], A>where
A: Allocator,
impl<T, A> From<Vec<T, A>> for Box<[T], A>where
A: Allocator,
source§fn from(v: Vec<T, A>) -> Box<[T], A>
fn from(v: Vec<T, A>) -> Box<[T], A>
Convert a vector into a boxed slice.
Before doing the conversion, this method discards excess capacity like Vec::shrink_to_fit
.
§Examples
assert_eq!(Box::from(vec![1, 2, 3]), vec![1, 2, 3].into_boxed_slice());
RunAny excess capacity is removed:
let mut vec = Vec::with_capacity(10);
vec.extend([1, 2, 3]);
assert_eq!(Box::from(vec), vec![1, 2, 3].into_boxed_slice());
Run1.32.0 · source§impl<I> FromIterator<I> for Box<[I]>
impl<I> FromIterator<I> for Box<[I]>
source§impl<'a, T> IntoIterator for &'a [T]
impl<'a, T> IntoIterator for &'a [T]
source§impl<'a, T> IntoIterator for &'a mut [T]
impl<'a, T> IntoIterator for &'a mut [T]
source§impl<A, B, const N: usize> PartialEq<&mut [B]> for [A; N]where
A: PartialEq<B>,
impl<A, B, const N: usize> PartialEq<&mut [B]> for [A; N]where
A: PartialEq<B>,
source§impl<T, U> PartialEq<&mut [U]> for Cow<'_, [T]>
impl<T, U> PartialEq<&mut [U]> for Cow<'_, [T]>
source§impl<T, U, A> PartialEq<&mut [U]> for Vec<T, A>
impl<T, U, A> PartialEq<&mut [U]> for Vec<T, A>
1.46.0 · source§impl<T, U, A> PartialEq<Vec<U, A>> for &[T]
impl<T, U, A> PartialEq<Vec<U, A>> for &[T]
1.46.0 · source§impl<T, U, A> PartialEq<Vec<U, A>> for &mut [T]
impl<T, U, A> PartialEq<Vec<U, A>> for &mut [T]
1.48.0 · source§impl<T, U, A> PartialEq<Vec<U, A>> for [T]
impl<T, U, A> PartialEq<Vec<U, A>> for [T]
source§impl<T> PartialOrd for [T]where
T: PartialOrd,
impl<T> PartialOrd for [T]where
T: PartialOrd,
Implements comparison of vectors lexicographically.
source§impl<'a, 'b> Pattern<'a> for &'b [char]
impl<'a, 'b> Pattern<'a> for &'b [char]
Searches for chars that are equal to any of the char
s in the slice.
§Examples
assert_eq!("Hello world".find(&['l', 'l'] as &[_]), Some(2));
assert_eq!("Hello world".find(&['l', 'l'][..]), Some(2));
Run§type Searcher = CharSliceSearcher<'a, 'b>
type Searcher = CharSliceSearcher<'a, 'b>
pattern
#27721)source§fn into_searcher(self, haystack: &'a str) -> CharSliceSearcher<'a, 'b>
fn into_searcher(self, haystack: &'a str) -> CharSliceSearcher<'a, 'b>
pattern
#27721)self
and the haystack
to search in.source§fn is_contained_in(self, haystack: &'a str) -> bool
fn is_contained_in(self, haystack: &'a str) -> bool
pattern
#27721)source§fn is_prefix_of(self, haystack: &'a str) -> bool
fn is_prefix_of(self, haystack: &'a str) -> bool
pattern
#27721)source§fn strip_prefix_of(self, haystack: &'a str) -> Option<&'a str>
fn strip_prefix_of(self, haystack: &'a str) -> Option<&'a str>
pattern
#27721)source§fn is_suffix_of(self, haystack: &'a str) -> boolwhere
CharSliceSearcher<'a, 'b>: ReverseSearcher<'a>,
fn is_suffix_of(self, haystack: &'a str) -> boolwhere
CharSliceSearcher<'a, 'b>: ReverseSearcher<'a>,
pattern
#27721)source§fn strip_suffix_of(self, haystack: &'a str) -> Option<&'a str>where
CharSliceSearcher<'a, 'b>: ReverseSearcher<'a>,
fn strip_suffix_of(self, haystack: &'a str) -> Option<&'a str>where
CharSliceSearcher<'a, 'b>: ReverseSearcher<'a>,
pattern
#27721)source§impl Read for &[u8]
impl Read for &[u8]
Read is implemented for &[u8]
by copying from the slice.
Note that reading updates the slice to point to the yet unread part. The slice will be empty when EOF is reached.
source§fn read(&mut self, buf: &mut [u8]) -> Result<usize>
fn read(&mut self, buf: &mut [u8]) -> Result<usize>
source§fn read_buf(&mut self, cursor: BorrowedCursor<'_>) -> Result<()>
fn read_buf(&mut self, cursor: BorrowedCursor<'_>) -> Result<()>
read_buf
#78485)source§fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize>
fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize>
read
, except that it reads into a slice of buffers. Read moresource§fn is_read_vectored(&self) -> bool
fn is_read_vectored(&self) -> bool
can_vector
#69941)source§fn read_exact(&mut self, buf: &mut [u8]) -> Result<()>
fn read_exact(&mut self, buf: &mut [u8]) -> Result<()>
buf
. Read moresource§fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize>
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize>
buf
. Read moresource§fn read_to_string(&mut self, buf: &mut String) -> Result<usize>
fn read_to_string(&mut self, buf: &mut String) -> Result<usize>
buf
. Read moresource§fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<()>
fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<()>
read_buf
#78485)cursor
. Read moresource§fn by_ref(&mut self) -> &mut Selfwhere
Self: Sized,
fn by_ref(&mut self) -> &mut Selfwhere
Self: Sized,
Read
. Read more1.53.0 · source§impl<T> SliceIndex<[T]> for (Bound<usize>, Bound<usize>)
impl<T> SliceIndex<[T]> for (Bound<usize>, Bound<usize>)
source§fn get(
self,
slice: &[T]
) -> Option<&<(Bound<usize>, Bound<usize>) as SliceIndex<[T]>>::Output>
fn get( self, slice: &[T] ) -> Option<&<(Bound<usize>, Bound<usize>) as SliceIndex<[T]>>::Output>
slice_index_methods
)source§fn get_mut(
self,
slice: &mut [T]
) -> Option<&mut <(Bound<usize>, Bound<usize>) as SliceIndex<[T]>>::Output>
fn get_mut( self, slice: &mut [T] ) -> Option<&mut <(Bound<usize>, Bound<usize>) as SliceIndex<[T]>>::Output>
slice_index_methods
)source§unsafe fn get_unchecked(
self,
slice: *const [T]
) -> *const <(Bound<usize>, Bound<usize>) as SliceIndex<[T]>>::Output
unsafe fn get_unchecked( self, slice: *const [T] ) -> *const <(Bound<usize>, Bound<usize>) as SliceIndex<[T]>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.source§unsafe fn get_unchecked_mut(
self,
slice: *mut [T]
) -> *mut <(Bound<usize>, Bound<usize>) as SliceIndex<[T]>>::Output
unsafe fn get_unchecked_mut( self, slice: *mut [T] ) -> *mut <(Bound<usize>, Bound<usize>) as SliceIndex<[T]>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.1.15.0 (const: unstable) · source§impl<T> SliceIndex<[T]> for Range<usize>
impl<T> SliceIndex<[T]> for Range<usize>
const: unstable · source§fn get(self, slice: &[T]) -> Option<&[T]>
fn get(self, slice: &[T]) -> Option<&[T]>
slice_index_methods
)const: unstable · source§fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>
fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>
slice_index_methods
)const: unstable · source§unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]
unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.const: unstable · source§unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]
unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.1.15.0 (const: unstable) · source§impl<T> SliceIndex<[T]> for RangeFrom<usize>
impl<T> SliceIndex<[T]> for RangeFrom<usize>
const: unstable · source§fn get(self, slice: &[T]) -> Option<&[T]>
fn get(self, slice: &[T]) -> Option<&[T]>
slice_index_methods
)const: unstable · source§fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>
fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>
slice_index_methods
)const: unstable · source§unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]
unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.const: unstable · source§unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]
unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.1.15.0 (const: unstable) · source§impl<T> SliceIndex<[T]> for RangeFull
impl<T> SliceIndex<[T]> for RangeFull
const: unstable · source§fn get(self, slice: &[T]) -> Option<&[T]>
fn get(self, slice: &[T]) -> Option<&[T]>
slice_index_methods
)const: unstable · source§fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>
fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>
slice_index_methods
)const: unstable · source§unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]
unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.const: unstable · source§unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]
unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.1.26.0 (const: unstable) · source§impl<T> SliceIndex<[T]> for RangeInclusive<usize>
impl<T> SliceIndex<[T]> for RangeInclusive<usize>
const: unstable · source§fn get(self, slice: &[T]) -> Option<&[T]>
fn get(self, slice: &[T]) -> Option<&[T]>
slice_index_methods
)const: unstable · source§fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>
fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>
slice_index_methods
)const: unstable · source§unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]
unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.const: unstable · source§unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]
unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.1.15.0 (const: unstable) · source§impl<T> SliceIndex<[T]> for RangeTo<usize>
impl<T> SliceIndex<[T]> for RangeTo<usize>
const: unstable · source§fn get(self, slice: &[T]) -> Option<&[T]>
fn get(self, slice: &[T]) -> Option<&[T]>
slice_index_methods
)const: unstable · source§fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>
fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>
slice_index_methods
)const: unstable · source§unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]
unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.const: unstable · source§unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]
unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.1.26.0 (const: unstable) · source§impl<T> SliceIndex<[T]> for RangeToInclusive<usize>
impl<T> SliceIndex<[T]> for RangeToInclusive<usize>
const: unstable · source§fn get(self, slice: &[T]) -> Option<&[T]>
fn get(self, slice: &[T]) -> Option<&[T]>
slice_index_methods
)const: unstable · source§fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>
fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>
slice_index_methods
)const: unstable · source§unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]
unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.const: unstable · source§unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]
unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.1.15.0 (const: unstable) · source§impl<T> SliceIndex<[T]> for usize
impl<T> SliceIndex<[T]> for usize
const: unstable · source§fn get(self, slice: &[T]) -> Option<&T>
fn get(self, slice: &[T]) -> Option<&T>
slice_index_methods
)const: unstable · source§fn get_mut(self, slice: &mut [T]) -> Option<&mut T>
fn get_mut(self, slice: &mut [T]) -> Option<&mut T>
slice_index_methods
)const: unstable · source§unsafe fn get_unchecked(self, slice: *const [T]) -> *const T
unsafe fn get_unchecked(self, slice: *const [T]) -> *const T
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.const: unstable · source§unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut T
unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut T
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.1.51.0 · source§impl<T> SlicePattern for [T]
impl<T> SlicePattern for [T]
1.8.0 · source§impl<'a> ToSocketAddrs for &'a [SocketAddr]
impl<'a> ToSocketAddrs for &'a [SocketAddr]
§type Iter = Cloned<Iter<'a, SocketAddr>>
type Iter = Cloned<Iter<'a, SocketAddr>>
source§fn to_socket_addrs(&self) -> Result<Self::Iter>
fn to_socket_addrs(&self) -> Result<Self::Iter>
SocketAddr
s. Read more1.34.0 · source§impl<'a, T, const N: usize> TryFrom<&'a [T]> for &'a [T; N]
impl<'a, T, const N: usize> TryFrom<&'a [T]> for &'a [T; N]
Tries to create an array ref &[T; N]
from a slice ref &[T]
. Succeeds if
slice.len() == N
.
let bytes: [u8; 3] = [1, 0, 2];
let bytes_head: &[u8; 2] = <&[u8; 2]>::try_from(&bytes[0..2]).unwrap();
assert_eq!(1, u16::from_le_bytes(*bytes_head));
let bytes_tail: &[u8; 2] = bytes[1..3].try_into().unwrap();
assert_eq!(512, u16::from_le_bytes(*bytes_tail));
Run§type Error = TryFromSliceError
type Error = TryFromSliceError
1.34.0 · source§impl<T, const N: usize> TryFrom<&[T]> for [T; N]where
T: Copy,
impl<T, const N: usize> TryFrom<&[T]> for [T; N]where
T: Copy,
Tries to create an array [T; N]
by copying from a slice &[T]
. Succeeds if
slice.len() == N
.
let bytes: [u8; 3] = [1, 0, 2];
let bytes_head: [u8; 2] = <[u8; 2]>::try_from(&bytes[0..2]).unwrap();
assert_eq!(1, u16::from_le_bytes(bytes_head));
let bytes_tail: [u8; 2] = bytes[1..3].try_into().unwrap();
assert_eq!(512, u16::from_le_bytes(bytes_tail));
Run§type Error = TryFromSliceError
type Error = TryFromSliceError
source§impl<T, const N: usize> TryFrom<&[T]> for Simd<T, N>
impl<T, const N: usize> TryFrom<&[T]> for Simd<T, N>
§type Error = TryFromSliceError
type Error = TryFromSliceError
1.34.0 · source§impl<'a, T, const N: usize> TryFrom<&'a mut [T]> for &'a mut [T; N]
impl<'a, T, const N: usize> TryFrom<&'a mut [T]> for &'a mut [T; N]
Tries to create a mutable array ref &mut [T; N]
from a mutable slice ref
&mut [T]
. Succeeds if slice.len() == N
.
let mut bytes: [u8; 3] = [1, 0, 2];
let bytes_head: &mut [u8; 2] = <&mut [u8; 2]>::try_from(&mut bytes[0..2]).unwrap();
assert_eq!(1, u16::from_le_bytes(*bytes_head));
let bytes_tail: &mut [u8; 2] = (&mut bytes[1..3]).try_into().unwrap();
assert_eq!(512, u16::from_le_bytes(*bytes_tail));
Run§type Error = TryFromSliceError
type Error = TryFromSliceError
1.59.0 · source§impl<T, const N: usize> TryFrom<&mut [T]> for [T; N]where
T: Copy,
impl<T, const N: usize> TryFrom<&mut [T]> for [T; N]where
T: Copy,
Tries to create an array [T; N]
by copying from a mutable slice &mut [T]
.
Succeeds if slice.len() == N
.
let mut bytes: [u8; 3] = [1, 0, 2];
let bytes_head: [u8; 2] = <[u8; 2]>::try_from(&mut bytes[0..2]).unwrap();
assert_eq!(1, u16::from_le_bytes(bytes_head));
let bytes_tail: [u8; 2] = (&mut bytes[1..3]).try_into().unwrap();
assert_eq!(512, u16::from_le_bytes(bytes_tail));
Run§type Error = TryFromSliceError
type Error = TryFromSliceError
source§impl<T, const N: usize> TryFrom<&mut [T]> for Simd<T, N>
impl<T, const N: usize> TryFrom<&mut [T]> for Simd<T, N>
§type Error = TryFromSliceError
type Error = TryFromSliceError
source§impl Write for &mut [u8]
impl Write for &mut [u8]
Write is implemented for &mut [u8]
by copying into the slice, overwriting
its data.
Note that writing updates the slice to point to the yet unwritten part. The slice will be empty when it has been completely overwritten.
If the number of bytes to be written exceeds the size of the slice, write operations will
return short writes: ultimately, Ok(0)
; in this situation, write_all
returns an error of
kind ErrorKind::WriteZero
.
source§fn write(&mut self, data: &[u8]) -> Result<usize>
fn write(&mut self, data: &[u8]) -> Result<usize>
source§fn is_write_vectored(&self) -> bool
fn is_write_vectored(&self) -> bool
can_vector
#69941)source§fn write_all(&mut self, data: &[u8]) -> Result<()>
fn write_all(&mut self, data: &[u8]) -> Result<()>
source§fn flush(&mut self) -> Result<()>
fn flush(&mut self) -> Result<()>
source§fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<()>
fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<()>
write_all_vectored
#70436)