How should I call Vec::with_capacity with an i32?

Question

I have a function which allocates a vector on the stack. This code doesn't work: ``` fn my_func(n: i32) { let mut v = Vec::with_capacity(n); } ``` The compiler says `n` needs to be a `usize`. I suppose that makes sense from a type safety point of view, but I need to use `n` in other calculations where an `i32` is called for. What's the proper way to handle this?

Accepted Answer

Cast to usize.

```
let n: i32 = 4;
let v = Vec::<i16>::with_capacity(n as usize);
```

How should I call Vec::with_capacity with an i32?

Solution

Problem