Bug: 270156988

Clone this repo:
  1. c7c9c6a Make crate apex-available by Ted Bauer · 3 weeks ago main master
  2. 5d6ab7a Revert "Upgrade fastrand to 2.0.1" am: a329b7310b by Hyun Jae Moon · 10 weeks ago emu-34-2-dev
  3. a329b73 Revert "Upgrade fastrand to 2.0.1" by Hyun Jae Moon · 10 weeks ago emu-34-3-release
  4. e614fb3 Upgrade fastrand to 2.0.1 am: f00a459d95 by Jeff Vander Stoep · 10 weeks ago
  5. f00a459 Upgrade fastrand to 2.0.1 by Jeff Vander Stoep · 10 weeks ago

fastrand

Build License Cargo Documentation

A simple and fast random number generator.

The implementation uses Wyrand, a simple and fast generator but not cryptographically secure.

Examples

Flip a coin:

if fastrand::bool() {
    println!("heads");
} else {
    println!("tails");
}

Generate a random i32:

let num = fastrand::i32(..);

Choose a random element in an array:

let v = vec![1, 2, 3, 4, 5];
let i = fastrand::usize(..v.len());
let elem = v[i];

Shuffle an array:

let mut v = vec![1, 2, 3, 4, 5];
fastrand::shuffle(&mut v);

Generate a random Vec or String:

use std::iter::repeat_with;

let v: Vec<i32> = repeat_with(|| fastrand::i32(..)).take(10).collect();
let s: String = repeat_with(fastrand::alphanumeric).take(10).collect();

To get reproducible results on every run, initialize the generator with a seed:

// Pick an arbitrary number as seed.
fastrand::seed(7);

// Now this prints the same number on every run:
println!("{}", fastrand::u32(..));

To be more efficient, create a new Rng instance instead of using the thread-local generator:

use std::iter::repeat_with;

let rng = fastrand::Rng::new();
let mut bytes: Vec<u8> = repeat_with(|| rng.u8(..)).take(10_000).collect();

License

Licensed under either of

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.