Function core::ptr::slice_from_raw_parts_mut
1.42.0 (const: unstable) · source · pub fn slice_from_raw_parts_mut<T>(data: *mut T, len: usize) -> *mut [T]
Expand description
Forms a raw mutable slice from a pointer and a length.
The len
argument is the number of elements, not the number of bytes.
Performs the same functionality as slice_from_raw_parts
, except that a
raw mutable slice is returned, as opposed to a raw immutable slice.
This function is safe, but actually using the return value is unsafe.
See the documentation of slice::from_raw_parts_mut
for slice safety requirements.
§Examples
use std::ptr;
let x = &mut [5, 6, 7];
let raw_pointer = x.as_mut_ptr();
let slice = ptr::slice_from_raw_parts_mut(raw_pointer, 3);
unsafe {
(*slice)[2] = 99; // assign a value at an index in the slice
};
assert_eq!(unsafe { &*slice }[2], 99);
You must ensure that the pointer is valid and not null before dereferencing the raw slice. A slice reference must never have a null pointer, even if it’s empty.
ⓘ
use std::ptr;
let danger: *mut [u8] = ptr::slice_from_raw_parts_mut(ptr::null_mut(), 0);
unsafe {
danger.as_mut().expect("references must not be null");
}