A Rust library for random number generators and other randomness functionality.
Add this to your
 = "0.4"
and this to your crate root:
extern crate rand;
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 (
0.5 is in development and contains significant performance
improvements for the ISAAC random number generators.
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.
let tuple = ; println!
use Rng; let mut rng = thread_rng; if rng.gen
It is also possible to use other RNG types, which have a similar interface. The following uses the "ChaCha" algorithm instead of the default.
use ; let mut rng = new_unseeded; println!
rand is built with all stable features available. The following
optional features are available:
i128_supportenables support for generating
nightlyenables all unstable features (
stdenabled by default; by setting "default-features = false"
no_stdmode is activated; this removes features depending on
- `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`
alloccan be used instead of
cargo test does not test everything. The following tests are
# Basic tests for rand and sub-crates cargo test --all # Test no_std support (build only since nearly all tests require std) cargo build --all --no-default-features # Test 128-bit support (requires nightly) cargo test --all --features nightly # Benchmarks (requires nightly) cargo bench # or just to test the benchmark code: cargo test --benches
You can derive the
Rand trait for your custom type via the
directive. To use this first add this to your Cargo.toml:
= "0.4" = "0.3"
Next in your crate:
extern crate rand; extern crate rand_derive;
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.