std::discrete_distribution (3) - Linux Manuals

std::discrete_distribution: std::discrete_distribution


std::discrete_distribution - std::discrete_distribution


Defined in header <random>
template< class IntType = int > (since C++11)
class discrete_distribution;

std::discrete_distribution produces random integers on the interval [0, n), where the probability of each individual integer i is defined as w
i/S, that is the weight of the ith integer divided by the sum of all n weights.
std::discrete_distribution satisfies all requirements of RandomNumberDistribution

Template parameters

IntType - The result type generated by the generator. The effect is undefined if this is not one of short, int, long, long long, unsigned short, unsigned int, unsigned long, or unsigned long long.

Member types

Member type Definition
result_type IntType
param_type the type of the parameter set, see RandomNumberDistribution.

Member functions

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


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


              obtains the list of probabilities
probabilities (public member function)
              gets or sets the distribution parameter object
param (public member function)
              returns the minimum potentially generated value
min (public member function)
              returns the maximum potentially generated value
max (public member function)

Non-member functions

           compares two distribution objects
operator== (function)
           performs stream input and output on pseudo-random number distribution
operator<< (function template)


// Run this code

  #include <iostream>
  #include <map>
  #include <random>

  int main()
      std::random_device rd;
      std::mt19937 gen(rd());
      std::discrete_distribution<> d({40, 10, 10, 40});
      std::map<int, int> m;
      for(int n=0; n<10000; ++n) {
      for(auto p : m) {
          std::cout << p.first << " generated " << p.second << " times\n";


  0 generated 4028 times
  1 generated 978 times
  2 generated 1012 times
  3 generated 3982 times