core::ptr::replace - Rust
Description: API documentation for the Rust `replace` fn in crate `core`.
Keywords: rust, rustlang, rust-lang, replace

# 1.0.0[−][src]Function core::ptr::replace

    pub unsafe fn replace<T>(dst: *mut T, src: T) -> T

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 type `T`.

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