rand::rngs

Struct StdRng

Source
pub struct StdRng(/* private fields */);
Expand description

A strong, fast (amortized), non-portable RNG

This is the “standard” 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 portable version, use the rand_chacha crate directly.)
  • CSPRNG: statistically good quality of randomness and unpredictable
  • Fast (amortized): the RNG is fast for bulk generation, but the cost of method calls is not consistent due to usage of an output buffer.

The current algorithm used is the ChaCha block cipher with 12 rounds. Please see this relevant rand issue for the discussion. This may change as new evidence of cipher security and performance becomes available.

§Seeding (construction)

This generator implements the SeedableRng trait. Any method may be used, but note that seed_from_u64 is not suitable for usage where security is important. Also note that, even with a fixed seed, output is not portable.

It is suggested to use a fresh seed direct from the OS as the most secure and convenient option:

let rng = StdRng::from_os_rng();

See also Seeding RNGs in the book.

§Generation

The generators implements RngCore and thus also Rng. See also the Random Values chapter in the book.

Trait Implementations§

Source§

impl Clone for StdRng

Source§

fn clone(&self) -> StdRng

Returns a copy of the value. Read more
1.0.0 · Source§

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
Source§

impl Debug for StdRng

Source§

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

Formats the value using the given formatter. Read more
Source§

impl PartialEq for StdRng

Source§

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

Tests for self and other values to be equal, and is used by ==.
1.0.0 · Source§

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
Source§

impl RngCore for StdRng

Source§

fn next_u32(&mut self) -> u32

Return the next random u32. Read more
Source§

fn next_u64(&mut self) -> u64

Return the next random u64. Read more
Source§

fn fill_bytes(&mut self, dst: &mut [u8])

Fill dest with random data. Read more
Source§

impl SeedableRng for StdRng

Source§

type Seed = [u8; 32]

Seed type, which is restricted to types mutably-dereferenceable as u8 arrays (we recommend [u8; N] for some N). Read more
Source§

fn from_seed(seed: Self::Seed) -> Self

Create a new PRNG using the given seed. Read more
Source§

fn seed_from_u64(state: u64) -> Self

Create a new PRNG using a u64 seed. Read more
Source§

fn from_rng(rng: &mut impl RngCore) -> Self

Create a new PRNG seeded from an infallible Rng. Read more
Source§

fn try_from_rng<R>(rng: &mut R) -> Result<Self, <R as TryRngCore>::Error>
where R: TryRngCore,

Create a new PRNG seeded from a potentially fallible Rng. Read more
Source§

fn from_os_rng() -> Self

Creates a new instance of the RNG seeded via getrandom. Read more
Source§

fn try_from_os_rng() -> Result<Self, Error>

Creates a new instance of the RNG seeded via getrandom without unwrapping potential getrandom errors. Read more
Source§

impl CryptoRng for StdRng

Source§

impl Eq for StdRng

Source§

impl StructuralPartialEq for StdRng

Auto Trait Implementations§

§

impl Freeze for StdRng

§

impl RefUnwindSafe for StdRng

§

impl Send for StdRng

§

impl Sync for StdRng

§

impl Unpin for StdRng

§

impl UnwindSafe for StdRng

Blanket Implementations§

Source§

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

Source§

fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
Source§

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

Source§

fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
Source§

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

Source§

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

Mutably borrows from an owned value. Read more
Source§

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

Source§

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

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dst. Read more
Source§

impl<T> From<T> for T

Source§

fn from(t: T) -> T

Returns the argument unchanged.

Source§

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

Source§

fn into(self) -> U

Calls U::from(self).

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

Source§

impl<R> Rng for R
where R: RngCore + ?Sized,

Source§

fn random<T>(&mut self) -> T

Return a random value via the StandardUniform distribution. Read more
Source§

fn random_iter<T>(self) -> DistIter<StandardUniform, Self, T>

Return an iterator over random variates Read more
Source§

fn random_range<T, R>(&mut self, range: R) -> T
where T: SampleUniform, R: SampleRange<T>,

Generate a random value in the given range. Read more
Source§

fn random_bool(&mut self, p: f64) -> bool

Return a bool with a probability p of being true. Read more
Source§

fn random_ratio(&mut self, numerator: u32, denominator: u32) -> bool

Return a bool with a probability of numerator/denominator of being true. Read more
Source§

fn sample<T, D: Distribution<T>>(&mut self, distr: D) -> T

Sample a new value, using the given distribution. Read more
Source§

fn sample_iter<T, D>(self, distr: D) -> DistIter<D, Self, T>
where D: Distribution<T>, Self: Sized,

Create an iterator that generates values using the given distribution. Read more
Source§

fn fill<T: Fill + ?Sized>(&mut self, dest: &mut T)

Fill any type implementing Fill with random data Read more
Source§

fn gen<T>(&mut self) -> T

👎Deprecated since 0.9.0: Renamed to random to avoid conflict with the new gen keyword in Rust 2024.
Alias for Rng::random.
Source§

fn gen_range<T, R>(&mut self, range: R) -> T
where T: SampleUniform, R: SampleRange<T>,

👎Deprecated since 0.9.0: Renamed to random_range
Source§

fn gen_bool(&mut self, p: f64) -> bool

👎Deprecated since 0.9.0: Renamed to random_bool
Alias for Rng::random_bool.
Source§

fn gen_ratio(&mut self, numerator: u32, denominator: u32) -> bool

👎Deprecated since 0.9.0: Renamed to random_ratio
Source§

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

Source§

type Owned = T

The resulting type after obtaining ownership.
Source§

fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
Source§

fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
Source§

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

Source§

type Error = Infallible

The type returned in the event of a conversion error.
Source§

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

Performs the conversion.
Source§

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

Source§

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
Source§

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

Performs the conversion.
Source§

impl<R> TryRngCore for R
where R: RngCore,

Source§

type Error = Infallible

The type returned in the event of a RNG error.
Source§

fn try_next_u32(&mut self) -> Result<u32, <R as TryRngCore>::Error>

Return the next random u32.
Source§

fn try_next_u64(&mut self) -> Result<u64, <R as TryRngCore>::Error>

Return the next random u64.
Source§

fn try_fill_bytes( &mut self, dst: &mut [u8], ) -> Result<(), <R as TryRngCore>::Error>

Fill dest entirely with random data.
Source§

fn unwrap_err(self) -> UnwrapErr<Self>
where Self: Sized,

Wrap RNG with the UnwrapErr wrapper.
Source§

fn read_adapter(&mut self) -> RngReadAdapter<'_, Self>
where Self: Sized,

Convert an RngCore to a RngReadAdapter.
Source§

impl<V, T> VZip<V> for T
where V: MultiLane<T>,

Source§

fn vzip(self) -> V

Source§

impl<R> TryCryptoRng for R
where R: CryptoRng,