Crate rand[][src]

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Utilities for random number generation

Rand provides utilities to generate random numbers, to convert them to useful types and distributions, and some randomness-related algorithms.

Quick Start

To get you started quickly, the easiest and highest-level way to get a random value is to use random(); alternatively you can use thread_rng(). The Rng trait provides a useful API on all RNGs, while the distributions and seq modules provide further functionality on top of RNGs.

use rand::prelude::*;

if rand::random() { // generates a boolean
    // Try printing a random unicode code point (probably a bad idea)!
    println!("char: {}", rand::random::<char>());

let mut rng = rand::thread_rng();
let y: f64 = rng.gen(); // generates a float between 0 and 1

let mut nums: Vec<i32> = (1..100).collect();
nums.shuffle(&mut rng);

The Book

For the user guide and further documentation, please read The Rust Rand Book.



Generating random samples from probability distributions


Convenience re-export of common members


Random number generators and adapters


Sequence-related functionality



Error type of random number generators



A marker trait used to indicate that an RngCore or BlockRngCore implementation is supposed to be cryptographically secure.


Types which may be filled with random data


An automatically-implemented extension trait on RngCore providing high-level generic methods for sampling values and other convenience methods.


The core of a random number generator.


A random number generator that can be explicitly seeded.


randomstd and std_rng

Generates a random value using the thread-local random number generator.

thread_rngstd and std_rng

Retrieve the lazily-initialized thread-local random number generator, seeded by the system. Intended to be used in method chaining style, e.g. thread_rng().gen::<i32>(), or cached locally, e.g. let mut rng = thread_rng();. Invoked by the Default trait, making ThreadRng::default() equivalent.