NAME¶

std::bernoulli_distribution - std::bernoulli_distribution

Synopsis¶

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 is true
1 − p, if b is false

std::bernoulli_distribution satisfies RandomNumberDistribution.

Member types¶

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

Member functions¶

constructor constructs new distribution
(C++11) (public member function)
reset resets the internal state of the distribution
(C++11) (public member function)

Generation¶

operator() generates the next random number in the distribution
(C++11) (public member function)

Characteristics¶

p returns the p distribution parameter (probability of generating true)
(C++11) (public member function)
param gets or sets the distribution parameter object
(C++11) (public member function)
min returns the minimum potentially generated value
(C++11) (public member function)
max returns the maximum potentially generated value
(C++11) (public member function)

Non-member functions¶

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

Example¶

// Run this code

#include <iomanip>
#include <iostream>
#include <map>
#include <random>
#include <string>

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)];

std::cout << std::boolalpha;
for (auto const& [key, value] : hist)
std::cout << std::setw(5) << key << ' '
<< std::string(value / 500, '*') << '\n';
}

Possible output:¶

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

External links¶

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