Struct `SmallRng`

pub struct SmallRng(/* private field */);

A small-state, fast, non-crypto, non-portable PRNG

This is the "standard small" RNG, a generator with the following properties:

Non-portable: any future library version may replace the algorithm and results may be platform-dependent. (For a small portable generator, use the rand_pcg or rand_xoshiro crate.)
Non-cryptographic: output is easy to predict (insecure)
Quality: statistically good quality
Fast: the RNG is fast for both bulk generation and single values, with consistent cost of method calls
Fast initialization
Small state: little memory usage (current state size is 16-32 bytes depending on platform)

The current algorithm is Xoshiro256PlusPlus on 64-bit platforms and Xoshiro128PlusPlus on 32-bit platforms. Both are also implemented by the rand_xoshiro crate.

Seeding (construction)

This generator implements the SeedableRng trait. All methods are suitable for seeding, but note that, even with a fixed seed, output is not portable. Some suggestions:

To automatically seed with a unique seed, use rand::make_rng():

use rand::rngs::SmallRng;
let mut rng: SmallRng = rand::make_rng();
# let _ = rand::Rng::next_u32(&mut rng);

To use a deterministic integral seed, use seed_from_u64. This uses a hash function internally to yield a (typically) good seed from any input.
```
# use rand::{SeedableRng, rngs::SmallRng};
let rng = SmallRng::seed_from_u64(1);
# let _: SmallRng = rng;
```
To seed deterministically from text or other input, use rand_seeder.

See also Seeding RNGs in the book.

Generation

The generator implements Rng and thus also RngExt. See also the Random Values chapter in the book.

Trait Implementations

`impl Clone for SmallRng`

fn clone(&self) -> SmallRng

`impl Debug for SmallRng`

fn fmt(&self, f: &mut Formatter<'_>) -> Result

`impl Eq for SmallRng`

`impl PartialEq for SmallRng`

fn eq(&self, other: &SmallRng) -> bool

`impl SeedableRng for SmallRng`

type Seed = [u8; 32];
fn from_seed(seed: Self::Seed) -> Self
fn seed_from_u64(state: u64) -> Self

`impl StructuralPartialEq for SmallRng`

`impl TryRng for SmallRng`

type Error = Infallible;
fn try_next_u32(&mut self) -> Result<u32, Infallible>
fn try_next_u64(&mut self) -> Result<u64, Infallible>
fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Infallible>

Auto Trait Implementations

`impl Freeze for SmallRng`

`impl RefUnwindSafe for SmallRng`

`impl Send for SmallRng`

`impl Sync for SmallRng`

`impl Unpin for SmallRng`

`impl UnsafeUnpin for SmallRng`

`impl UnwindSafe for SmallRng`

Blanket Implementations

`impl<R> Rng for SmallRng where R: TryRng<Error = Infallible> + ?Sized,`

fn next_u32(&mut self) -> u32
fn next_u64(&mut self) -> u64
fn fill_bytes(&mut self, dst: &mut [u8])

`impl<R> RngCore for SmallRng where R: Rng,`

`impl<R> RngExt for SmallRng where R: Rng + ?Sized,`

`impl<R> TryRngCore for SmallRng where R: TryRng,`

type Error = <R as TryRng>::Error;

`impl<T> Any for SmallRng where T: 'static + ?Sized,`

fn type_id(&self) -> TypeId

`impl<T> Borrow<T> for SmallRng where T: ?Sized,`

fn borrow(&self) -> &T

`impl<T> BorrowMut<T> for SmallRng where T: ?Sized,`

fn borrow_mut(&mut self) -> &mut T

`impl<T> CloneToUninit for SmallRng where T: Clone,`

unsafe fn clone_to_uninit(&self, dest: *mut u8)

`impl<T> From<T> for SmallRng`

fn from(t: T) -> T: Returns the argument unchanged.

`impl<T> ToOwned for SmallRng where T: Clone,`

type Owned = T;
fn to_owned(&self) -> T
fn clone_into(&self, target: &mut T)

`impl<T, U> Into<U> for SmallRng where U: From<T>,`

fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of [From]<T> for U chooses to do.

`impl<T, U> TryFrom<U> for SmallRng where U: Into<T>,`

type Error = Infallible;
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

`impl<T, U> TryInto<U> for SmallRng where U: TryFrom<T>,`

type Error = <U as TryFrom<T>>::Error;
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>