# Struct rand::os::OsRng [−] [src]

    pub struct OsRng(_);

A random number generator that retrieves randomness straight from the operating system. Platform sources:

- Unix-like systems (Linux, Android, Mac OSX): read directly from `/dev/urandom`, or from `getrandom(2)` system call if available.
- OpenBSD: calls `getentropy(2)`
- FreeBSD: uses the `kern.arandom` `sysctl(2)` mib
- Windows: calls `RtlGenRandom`, exported from `advapi32.dll` as `SystemFunction036`.
- iOS: calls SecRandomCopyBytes as /dev/(u)random is sandboxed.
- PNaCl: calls into the `nacl-irt-random-0.1` IRT interface.

This usually does not block. On some systems (e.g. FreeBSD, OpenBSD, Max OS X, and modern Linux) this may block very early in the init process, if the CSPRNG has not been seeded yet.[1]

[1] See https://www.python.org/dev/peps/pep-0524/ for a more in-depth discussion.

## Methods

### `impl OsRng`
[src]

#### `pub fn new() -> Result<OsRng>`
[src]

Create a new `OsRng`.

## Trait Implementations

### `impl Rng for OsRng`
[src]

#### `fn next_u32(&mut self) -> u32`
[src]

Return the next random u32. Read more

#### `fn next_u64(&mut self) -> u64`
[src]

Return the next random u64. Read more

#### `fn fill_bytes(&mut self, v: &mut [u8])`
[src]

Fill `dest` with random data. Read more

#### `fn next_f32(&mut self) -> f32`
[src]

Return the next random f32 selected from the half-open interval `[0, 1)`. Read more

#### `fn next_f64(&mut self) -> f64`
[src]

Return the next random f64 selected from the half-open interval `[0, 1)`. Read more

#### `fn gen<T: Rand>(&mut self) -> T where
Self: Sized,`
[src]

Return a random value of a `Rand` type. Read more

####
ⓘImportant traits for Generator<'a, T, R>

### Important traits for Generator<'a, T, R>

`impl<'a, T: Rand, R: Rng> Iterator for Generator<'a, T, R> type Item = T;`
`fn gen_iter<'a, T: Rand>(&'a mut self) -> Generator<'a, T, Self> where
Self: Sized,`
[src]

Return an iterator that will yield an infinite number of randomly generated items. Read more

#### `fn gen_range<T: PartialOrd + SampleRange>(&mut self, low: T, high: T) -> T where
Self: Sized,`
[src]

Generate a random value in the range [`low`, `high`). Read more

#### `fn gen_weighted_bool(&mut self, n: u32) -> bool where
Self: Sized,`
[src]

Return a bool with a 1 in n chance of true Read more

####
ⓘImportant traits for AsciiGenerator<'a, R>

### Important traits for AsciiGenerator<'a, R>

`impl<'a, R: Rng> Iterator for AsciiGenerator<'a, R> type Item = char;`
`fn gen_ascii_chars<'a>(&'a mut self) -> AsciiGenerator<'a, Self> where
Self: Sized,`
[src]

Return an iterator of random characters from the set A-Z,a-z,0-9. Read more

#### `fn choose<'a, T>(&mut self, values: &'a [T]) -> Option<&'a T> where
Self: Sized,`
[src]

Return a random element from `values`. Read more

#### `fn choose_mut<'a, T>(&mut self, values: &'a mut [T]) -> Option<&'a mut T> where
Self: Sized,`
[src]

Return a mutable pointer to a random element from `values`. Read more

#### `fn shuffle<T>(&mut self, values: &mut [T]) where
Self: Sized,`
[src]

Shuffle a mutable slice in place. Read more

### `impl Debug for OsRng`
[src]

#### `fn fmt(&self, f: &mut Formatter) -> Result`
[src]

Formats the value using the given formatter. Read more

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