std::random_device

 

C++

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Pseudo-random number generation

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independent_bits_engine (C++11)

shuffle_order_engine (C++11)

Generators

random_device (C++11)

Distributions

Uniform distributions

uniform_int_distribution (C++11)

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generate_canonical (C++11)

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bernoulli_distribution (C++11)

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geometric_distribution (C++11)

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poisson_distribution (C++11)

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weibull_distribution (C++11)

extreme_value_distribution (C++11)

Normal distributions

normal_distribution (C++11)

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chi_squared_distribution (C++11)

cauchy_distribution (C++11)

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student_t_distribution (C++11)

Sampling distributions

discrete_distribution (C++11)

piecewise_constant_distribution (C++11)

piecewise_linear_distribution (C++11)

Seed Sequences

seed_seq (C++11)

C library

rand

srand

RAND_MAX

 

std::random_device

Member functions

random_device::random_device

Generation

random_device::operator()

Characteristics

random_device::entropy

random_device::min

random_device::max

 

Defined in header <random>
class random_device;		(since C++11)

std::random_device is a uniformly-distributed integer random number generator, which produces non-deterministic random numbers, if a non-deterministic source (e.g. a hardware device) is available to the implementation.

Member types

Member type	Definition
result_type	unsigned int

Member functions

Construction
(constructor)	constructs the engine (public member function)
operator= (deleted)	the assignment operator is deleted (public member function)
Generation
operator()	advances the engine's state and returns the generated value (public member function)
Characteristics
entropy	obtains the entropy estimate for the non-deterministic random number generator (public member function)
min [static]	gets the smallest possible value in the output range (public static member function)
max [static]	gets the largest possible value in the output range (public static member function)

Example

#include <iostream>
#include <string>
#include <map>
#include <random>
int main()
{
    std::random_device rd;
    std::map<int, int> hist;
    for(int n=0; n<20000; ++n)
        ++hist[rd()%10];
    for(auto p : hist)
        std::cout << p.first << " : " << std::string(p.second/100, '*') << '\n';
}

Output:

0 : ********************
1 : *******************
2 : ********************
3 : ********************
4 : ********************
5 : *******************
6 : ********************
7 : ********************
8 : *******************
9 : ********************