pub unsafe fn replace<T>(dst: *mut T, src: T) -> T
Expand description
Moves src
into the pointed dst
, returning the previous dst
value.
Neither value is dropped.
This function is semantically equivalent to mem::replace
except that it
operates on raw pointers instead of references. When references are
available, mem::replace
should be preferred.
§Safety
Behavior is undefined if any of the following conditions are violated:
-
dst
must be valid for both reads and writes. -
dst
must be properly aligned. -
dst
must point to a properly initialized value of typeT
.
Note that even if T
has size 0
, the pointer must be non-null and properly aligned.
§Examples
use std::ptr;
let mut rust = vec!['b', 'u', 's', 't'];
// `mem::replace` would have the same effect without requiring the unsafe
// block.
let b = unsafe {
ptr::replace(&mut rust[0], 'r')
};
assert_eq!(b, 'b');
assert_eq!(rust, &['r', 'u', 's', 't']);
Run