header

# <random>

Random
This header introduces random number generation facilities.

This library allows to produce random numbers using combinations of generators and distributions:
• Generators: Objects that generate uniformly distributed numbers.
• Distributions: Objects that transform sequences of numbers generated by a generator into sequences of numbers that follow a specific random variable distribution, such as uniform, Normal or Binomial.

Distribution objects generate random numbers by means of their operator() member, which takes a generator object as argument:
 ``123`` ``````std::default_random_engine generator; std::uniform_int_distribution distribution(1,6); int dice_roll = distribution(generator); // generates number in the range 1..6 ``````

For repeated uses, both can be bound together:
 ``12`` ``````auto dice = std::bind ( distribution, generator ); int wisdom = dice()+dice()+dice();``````

Except for random_device, all standard generators defined in the library are random number engines, which are a kind of generators that use a particular algorithm to generate series of pseudo-random numbers. These algorithms need a seed as a source of randomness, and this seed can either be a single value or an object with a very specific generate() member function (see seed_seq for more info). A typical source of randomness for trivial tasks is time, such as the information provided by time or system_clock::now (for a typical example, see uniform_int_distribution::operator()).

As an alternative, trivial random numbers can also be generated using cstdlib's functions rand and srand.

### Generators

#### Pseudo-random number engines (templates)

Generators that use an algorithm to generate pseudo-random numbers based on an initial seed:

#### Engine adaptors

They adapt an engine, modifying the way numbers are generated with it:

#### Pseudo-random number engines (instantiations)

Particular instantiations of generator engines and adaptors:

#### Random number generators

Non-deterministic random number generator: