rand
====
A Rust library for random number generators and other randomness functionality.
[](https://travis-ci.org/rust-lang-nursery/rand)
[](https://ci.appveyor.com/project/alexcrichton/rand)
[Documentation](https://docs.rs/rand)
## Compatibility upgrade
Version 0.3 has been replaced by a compatibility wrapper around `rand` 0.4. It
is recommended to update to 0.4.
## Usage
Add this to your `Cargo.toml`:
```toml
[dependencies]
rand = "0.4"
```
and this to your crate root:
```rust
extern crate rand;
```
## 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.
```rust
let tuple = rand::random::<(f64, char)>();
println!("{:?}", tuple)
```
```rust
use rand::Rng;
let mut rng = rand::thread_rng();
if rng.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.
```rust
use rand::{Rng, ChaChaRng};
let mut rng = rand::ChaChaRng::new_unseeded();
println!("i32: {}, u32: {}", rng.gen::<i32>(), rng.gen::<u32>())
```
# `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:
```toml
rand = "0.4"
rand_derive = "0.3"
```
Next in your crate:
```rust
extern crate rand;
#[macro_use]
extern crate rand_derive;
#[derive(Rand, Debug)]
struct MyStruct {
a: i32,
b: u32,
}
fn main() {
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.