How can I modify a part of bigger slice or Vec with another smaller slice?

Question

How can I correctly implement this code below?

let mut bigger: [u8; 100] = [0u8; 100];
let smaller: [u8; 3] = [1, 2, 3];

// do something like: 
// bigger[0..3] = smaller;

Answer 1

Use copy_from_slice:

bigger[0..3].copy_from_slice(&smaller);

^(Playground)