Defined in header <random>  

template< class IntType = int > class discrete_distribution;  (since C++11) 
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 i
th integer divided by the sum of all n
weights.
std::discrete_distribution
satisfies all requirements of RandomNumberDistribution
.
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 type  Definition 

result_type  IntType 
param_type  the type of the parameter set, see RandomNumberDistribution . 
constructs new distribution (public member function) 

resets the internal state of the distribution (public member function) 

Generation 

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

Characteristics 

obtains the list of probabilities (public member function) 

gets or sets the distribution parameter object (public member function) 

returns the minimum potentially generated value (public member function) 

returns the maximum potentially generated value (public member function) 
compares two distribution objects (function) 

performs stream input and output on pseudorandom number distribution (function template) 
#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) { ++m[d(gen)]; } for(auto p : m) { std::cout << p.first << " generated " << p.second << " times\n"; } }
Output:
0 generated 4028 times 1 generated 978 times 2 generated 1012 times 3 generated 3982 times
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