Expand description
A simple and fast random number generator.
The implementation uses Wyrand, a simple and fast generator but not cryptographically secure.
Examples
Flip a coin:
if fastrand::bool() {
println!("heads");
} else {
println!("tails");
}
Generate a random i32
:
let num = fastrand::i32(..);
Choose a random element in an array:
let v = vec![1, 2, 3, 4, 5];
let i = fastrand::usize(..v.len());
let elem = v[i];
Shuffle an array:
let mut v = vec![1, 2, 3, 4, 5];
fastrand::shuffle(&mut v);
Generate a random Vec
or String
:
use std::iter::repeat_with;
let v: Vec<i32> = repeat_with(|| fastrand::i32(..)).take(10).collect();
let s: String = repeat_with(fastrand::alphanumeric).take(10).collect();
To get reproducible results on every run, initialize the generator with a seed:
// Pick an arbitrary number as seed.
fastrand::seed(7);
// Now this prints the same number on every run:
println!("{}", fastrand::u32(..));
To be more efficient, create a new Rng
instance instead of using the thread-local
generator:
use std::iter::repeat_with;
let rng = fastrand::Rng::new();
let mut bytes: Vec<u8> = repeat_with(|| rng.u8(..)).take(10_000).collect();
Structs
A random number generator.
Functions
Generates a random char
in ranges a-z and A-Z.
Generates a random char
in ranges a-z, A-Z and 0-9.
Generates a random bool
.
Generates a random char
in the given range.
Generates a random digit in the given base
.
Generates a random f32
in range 0..1
.
Generates a random f64
in range 0..1
.
Generates a random i8
in the given range.
Generates a random i16
in the given range.
Generates a random i32
in the given range.
Generates a random i64
in the given range.
Generates a random i128
in the given range.
Generates a random isize
in the given range.
Generates a random char
in range a-z.
Initializes the thread-local generator with the given seed.
Shuffles a slice randomly.
Generates a random u8
in the given range.
Generates a random u16
in the given range.
Generates a random u32
in the given range.
Generates a random u64
in the given range.
Generates a random u128
in the given range.
Generates a random char
in range A-Z.
Generates a random usize
in the given range.