Function core::mem::size_of_val_raw[][src]

pub unsafe fn size_of_val_raw<T: ?Sized>(val: *const T) -> usize
🔬 This is a nightly-only experimental API. (layout_for_ptr #69835)

Returns the size of the pointed-to value in bytes.

This is usually the same as size_of::<T>(). However, when T has no statically-known size, e.g., a slice [T] or a trait object, then size_of_val_raw can be used to get the dynamically-known size.

Safety

This function is only safe to call if the following conditions hold:

Examples

#![feature(layout_for_ptr)]
use std::mem;

assert_eq!(4, mem::size_of_val(&5i32));

let x: [u8; 13] = [0; 13];
let y: &[u8] = &x;
assert_eq!(13, unsafe { mem::size_of_val_raw(y) });
Run