binomial_distribution::operator()

Returns a random value.

template<class Engine>
    result_type operator()(Engine& eng);
template<class Engine>
    result_type operator()(Engine& eng,
        const param_type& par0);

Engine

The type of the random engine.

eng

The random engine.

par0

The parameter package used to return the random value.

The first member function uses the engine eng as a source of uniformly distributed random integral values and returns integral values with each value i occurring with probability pr(i) = comb(stored_t, i) * stored_p^i * (1 - stored_p)^(stored_t-i), where comb(t, i) is the number of possible combinations of t objects taken i at a time.

The second member function behaves the same, except that it uses the parameters stored in par0.

 

// std_tr1__random__binomial_distribution_operator_fn.cpp 
// compile with: /EHsc 
#include <random> 
#include <iostream> 
 
typedef std::mt19937 Myeng; 
typedef std::binomial_distribution<int, double> Mydist; 
int main() 
    { 
    Myeng eng; 
    Mydist dist(2, 0.6); 
    Mydist::input_type engval = eng(); 
    Mydist::result_type distval = dist(eng); 
 
    distval = distval;  // to quiet "unused" warnings 
    engval = engval; 
 
    std::cout << "p == " << dist.p() << std::endl; 
    std::cout << "t == " << dist.t() << std::endl; 
 
    dist.reset(); // discard any cached values 
    std::cout << "a random value == " << dist(eng) << std::endl; 
    std::cout << "a random value == " << dist(eng) << std::endl; 
    std::cout << "a random value == " << dist(eng) << std::endl; 
 
    return (0); 
    } 
 
p == 0.6
t == 2
a random value == 1
a random value == 0
a random value == 1

Header: <random>

Namespace: std

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