std::bernoulli_distribution

 

C++

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Named requirements

Feature test macros (C++20)

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Symbols index

External libraries

 

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random_device (C++11)

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uniform_int_distribution (C++11)

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Bernoulli distributions

bernoulli_distribution (C++11)

binomial_distribution (C++11)

negative_binomial_distribution (C++11)

geometric_distribution (C++11)

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poisson_distribution (C++11)

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normal_distribution (C++11)

lognormal_distribution (C++11)

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discrete_distribution (C++11)

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seed_seq (C++11)

C library

rand

srand

RAND_MAX

 

std::bernoulli_distribution

Member functions

bernoulli_distribution::bernoulli_distribution (C++11)

bernoulli_distribution::reset (C++11)

Generation

bernoulli_distribution::operator() (C++11)

Characteristics

bernoulli_distribution::p (C++11)

bernoulli_distribution::param (C++11)

bernoulli_distribution::min (C++11)

bernoulli_distribution::max (C++11)

Non-member functions

operator==operator!= (C++11)(C++11)(until C++20)

operator<<operator>> (C++11)(C++11)

 

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

Produces random boolean values, according to the discrete probability function. The probability of true is

P(b|p) =⎧
⎨
⎩p if b == true 
1 − p if b == false

std::bernoulli_distribution satisfies RandomNumberDistribution

Member types

Member type	Definition
result_type	bool
param_type(C++11)	the type of the parameter set, see RandomNumberDistribution.

Member functions

(constructor) (C++11)	constructs new distribution (public member function)
reset (C++11)	resets the internal state of the distribution (public member function)
Generation
operator() (C++11)	generates the next random number in the distribution (public member function)
Characteristics
p	returns the p distribution parameter (probability of generating true) (public member function)
param (C++11)	gets or sets the distribution parameter object (public member function)
min (C++11)	returns the minimum potentially generated value (public member function)
max (C++11)	returns the maximum potentially generated value (public member function)

Non-member functions

operator==operator!= (C++11)(C++11)(removed in C++20)	compares two distribution objects (function)
operator<<operator>> (C++11)	performs stream input and output on pseudo-random number distribution (function template)

Example

Run this code

#include <iostream>
#include <iomanip>
#include <string>
#include <map>
#include <random>
 
int main()
{
    std::random_device rd;
    std::mt19937 gen(rd());
    // give "true" 1/4 of the time
    // give "false" 3/4 of the time
    std::bernoulli_distribution d(0.25);
 
    std::map<bool, int> hist;
    for(int n=0; n<10000; ++n) {
        ++hist[d(gen)];
    }
    for(auto p : hist) {
        std::cout << std::boolalpha << std::setw(5) << p.first
                  << ' ' << std::string(p.second/500, '*') << '\n';
    }
}

Possible output:

false ***************
 true ****

External links

Weisstein, Eric W. "Bernoulli Distribution." From MathWorld--A Wolfram Web Resource.