rust-lang-nursery/rand

Name: rand

Owner: rust-lang-nursery

Description: null

Created: 2015-02-03 05:59:32.0

Updated: 2018-01-17 13:46:57.0

Pushed: 2018-01-18 18:45:25.0

Homepage: https://docs.rs/rand

Size: 84342

Language: Rust

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README

rand

A Rust library for random number generators and other randomness functionality.

Documentation

Usage

Add this to your Cargo.toml:

endencies]
 = "0.4"

and this to your crate root:

rn crate rand;

Versions

Version 0.4was released in December 2017. It contains almost no breaking changes since the 0.3 series, but nevertheless contains some significant new code, including a new “external” entropy source (JitterRng) and no_std support.

Version 0.5 is in development and will contain significant breaking changes.

Examples

There is built-in support for a random number generator (RNG) associated with each thread stored in thread-local storage. This RNG can be accessed via thread_rng, or used implicitly via random. This RNG is normally randomly seeded from an operating-system source of randomness, e.g. /dev/urandom on Unix systems, and will automatically reseed itself from this source after generating 32 KiB of random data.

tuple = rand::random::<(f64, char)>();
tln!("{:?}", tuple)

ust
rand::Rng;

mut rng = rand::thread_rng();
ng.gen() { // random bool
println!("i32: {}, u32: {}", rng.gen::<i32>(), rng.gen::<u32>())

It is also possible to use other RNG types, which have a similar interface. The following uses the “ChaCha” algorithm instead of the default.

rand::{Rng, ChaChaRng};

mut rng = rand::ChaChaRng::new_unseeded();
tln!("i32: {}, u32: {}", rng.gen::<i32>(), rng.gen::<u32>())

Features

By default, rand is built with all stable features available. The following optional features are available:

• alloc can be used instead of std to provide Vec and Box
• i128_support enables support for generating u128 and i128 values
• log enables some logging via the log crate
• nightly enables all unstable features (i128_support)
• serde-1 enables serialisation for some types, via Serde version 1
• std enabled by default; by setting “default-features = false” no_std mode is activated; this removes features depending on std functionality:
  • OsRng is entirely unavailable
  • JitterRng code is still present, but a nanosecond timer must be provided via JitterRng::new_with_timer
  • Since no external entropy is available, it is not possible to create generators with fresh seeds (user must provide entropy)
  • thread_rng, weak_rng and random are all disabled
  • exponential, normal and gamma type distributions are unavailable since exp and log functions are not provided in core
  • any code requiring Vec or Box

Testing

Unfortunately, cargo test does not test everything. The following tests are recommended:

sic tests for rand and sub-crates
o test --all

st no_std support (build only since nearly all tests require std)
o build --all --no-default-features

st 128-bit support (requires nightly)
o test --all --features nightly

nchmarks (requires nightly)
o bench
 just to test the benchmark code:
o test --benches

derive(Rand)

You can derive the Rand trait for your custom type via the #[derive(Rand)] directive. To use this first add this to your Cargo.toml:

 = "0.4"
_derive = "0.3"

Next in your crate:

rn crate rand;
cro_use]
rn crate rand_derive;

rive(Rand, Debug)]
ct MyStruct {
a: i32,
b: u32,


ain() {
println!("{:?}", rand::random::<MyStruct>());

License

rand is primarily distributed under the terms of both the MIT license and the Apache License (Version 2.0).

See LICENSE-APACHE, and LICENSE-MIT for details.