/C++

# std::bernoulli_distribution

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

(C++11)
constructs new distribution
(public member function)
(C++11)
resets the internal state of the distribution
(public member function)
##### Generation
(C++11)
generates the next random number in the distribution
(public member function)
##### Characteristics
returns the p distribution parameter (probability of generating `true`)
(public member function)
(C++11)
gets or sets the distribution parameter object
(public member function)
(C++11)
returns the minimum potentially generated value
(public member function)
(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<> (C++11) performs stream input and output on pseudo-random number distribution (function template)

### Example

```#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 ****```

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