How to slice a large Vec as &[u8]?

Question

I don\'t know how to convert a Vec into a &[u8] slice.

fn main() {
    let v: Vec = vec![1; 100_000_000];         


        

Answer 1

You can use std::slice::from_raw_parts:

let v_bytes: &[u8] = unsafe {
    std::slice::from_raw_parts(
        v.as_ptr() as *const u8,
        v.len() * std::mem::size_of::(),
    )
};

Following the comments on this answer, you should wrap this code in a function and have the return value borrow the input, so that you use the borrow checker as far as possible:

fn as_u8_slice(v: &[i32]) -> &[u8] {
    unsafe {
        std::slice::from_raw_parts(
            v.as_ptr() as *const u8,
            v.len() * std::mem::size_of::(),
        )
    }
}