[−][src]Crate fastrand
A simple random number generator.
The implementation uses PCG XSH RR 64/32, 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
Rng | A random number generator. |
Functions
alphabetic | Generates a random |
alphanumeric | Generates a random |
bool | Generates a random |
digit | Generates a random digit in the given |
f32 | Generates a random |
f64 | Generates a random |
i8 | Generates a random |
i16 | Generates a random |
i32 | Generates a random |
i64 | Generates a random |
i128 | Generates a random |
isize | Generates a random |
lowercase | Generates a random |
seed | Initializes the thread-local generator with the given seed. |
shuffle | Shuffles a slice randomly. |
u8 | Generates a random |
u16 | Generates a random |
u32 | Generates a random |
u64 | Generates a random |
u128 | Generates a random |
uppercase | Generates a random |
usize | Generates a random |