16

Is there an idiomatic way of initialising arrays in Rust. I'm creating an array of random numbers and was wondering if there is a more idiomatic way then just doing a for loop. My current code works fine, but seems more like C than proper Rust:

let mut my_array: [u64; 8] = [0; 8];
for i in 0..my_array.len() {
    my_array[i] = some_function();
}
Shepmaster
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SquattingSlavInTracksuit
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  • You may find this [Q & A](https://stackoverflow.com/questions/45282970/does-rust-have-an-equivalent-to-pythons-list-comprehension-syntax) helpful. Basically you can use a list comprehension to initialize your array. – Onorio Catenacci Mar 20 '18 at 15:34

2 Answers2

14

Various sized arrays can be directly randomly generated:

use rand; // 0.7.3

fn main() {
    let my_array: [u64; 8] = rand::random();
    println!("{:?}", my_array);
}

Currently, this only works for arrays of size from 0 to 32 (inclusive). Beyond that, you will want to see related questions:

Shepmaster
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1

The other solution is nice and short, but does not apply to the case where you need to initialize an array of random numbers in a specific range. So, here's an answer that addresses that case.

use rand::{thread_rng, Rng};

fn main() {
    let a = [(); 8].map(|_| thread_rng().gen_range(0.0..1.0));
    println!("The array of random float numbers between 0.0 and 1.0 is: {:?}", a);
}

I would be happy to know if there's a better (shorter and more efficient) solution than this one.

nbro
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