Allocate array onto heap with size known at runtime

Question

In C++, I could put an array of 1000 ints onto the heap like this:

int size = 1000;
int* values = new in         


        

Answer 1

Arrays in Rust are fixed-length. If you want a dynamically-sized array, use Vec. In this case, the simplest way is with the vec! macro:

let size = 1000;
let values = vec![0; size];

Also, if you're super concerned about Vec being three words long and don't need to resize the storage after it's created, you can explicitly discard the internal capacity, and bring values down to two words on the stack:

let values = values.into_boxed_slice(); // returns a Box<[i32]>.