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 == 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 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)
(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 <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.