swap_nonoverlapping in std::ptr - Rust (original) (raw)

Function swap_nonoverlapping

1.27.0 (const: unstable) · Source

pub unsafe fn swap_nonoverlapping<T>(x: *mut T, y: *mut T, count: usize)

Expand description

Swaps count * size_of::<T>() bytes between the two regions of memory beginning at x and y. The two regions must not overlap.

The operation is “untyped” in the sense that data may be uninitialized or otherwise violate the requirements of T. The initialization state is preserved exactly.

§Safety

Behavior is undefined if any of the following conditions are violated:

• Both x and y must be valid for both reads and writes of count * size_of::<T>() bytes.
• Both x and y must be properly aligned.
• The region of memory beginning at x with a size of count * size_of::<T>() bytes must not overlap with the region of memory beginning at y with the same size.

Note that even if the effectively copied size (count * size_of::<T>()) is 0, the pointers must be properly aligned.

§Examples

Basic usage:

use std::ptr;

let mut x = [1, 2, 3, 4];
let mut y = [7, 8, 9];

unsafe {
    ptr::swap_nonoverlapping(x.as_mut_ptr(), y.as_mut_ptr(), 2);
}

assert_eq!(x, [7, 8, 3, 4]);
assert_eq!(y, [1, 2, 9]);