Crate rand

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

// The prelude import enables methods we use below, specifically
// Rng::random, Rng::sample, SliceRandom::shuffle and IndexedRandom::choose.
use rand::prelude::*;

// Get an RNG:
let mut rng = rand::rng();

// Try printing a random unicode code point (probably a bad idea)!
println!("char: '{}'", rng.random::<char>());
// Try printing a random alphanumeric value instead!
println!("alpha: '{}'", rng.sample(rand::distr::Alphanumeric) as char);

// Generate and shuffle a sequence:
let mut nums: Vec<i32> = (1..100).collect();
nums.shuffle(&mut rng);
// And take a random pick (yes, we didn't need to shuffle first!):
let _ = nums.choose(&mut rng);

The Book

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

Modules

distr

Generating random samples from probability distributions

prelude

Convenience re-export of common members

rngs

Random number generators and adapters

seq

Sequence-related functionality

Traits

CryptoRng

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

Fill

Types which may be filled with random data

Rng

User-level interface for RNGs

RngCore

Implementation-level interface for RNGs

SeedableRng

A random number generator that can be explicitly seeded.

TryCryptoRng

A marker trait used to indicate that a TryRngCore implementation is supposed to be cryptographically secure.

TryRngCore

A potentially fallible variant of RngCore

Functions

fillthread_rng

Fill any type implementing Fill with random data

randomthread_rng

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

random_boolthread_rng

Return a bool with a probability p of being true.

random_iterthread_rng

Return an iterator over random() variates

random_rangethread_rng

Generate a random value in the given range using the thread-local random number generator.

random_ratiothread_rng

Return a bool with a probability of numerator/denominator of being true.

rngthread_rng

Access a fast, pre-initialized generator

thread_rngDeprecatedthread_rng

Access the thread-local generator