uniform_int_distribution in C++

Uniform_int_distribution is a class template. uniform _int_distribution or you can say random number distribution, produces an integer value by using the uniform discrete distribution which is this function:

This distribution produces random integers in a range of a and b [a, b]. In other words it returns a new random number that follows the parameters. Since it is a class template, we have to call its member function operator to produce a random value. uniform_int_distribution is used for generating random numbers within a range and the range is in between a and b.

Member functions

All the member functions given in the table are public member function.

Distribution parameters

a --> Lower range
b --> Upper range

Return value

It returns a random integer value since it is generating a random number.

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title: "uniform_int_distribution in c++"
tags: cpp, oop

canonical_url: https://kodlogs.com/blog/689/uniform_int_distribution-in-c

Examples

// uniform_int_distribution::operator()
#include <iostream>
#include <chrono>
#include <random>

int main()
{
  // construct a trivial random generator engine from a time-based seed:
  unsigned seed = std::chrono::system_clock::now().time_since_epoch().count();
  std::default_random_engine generator (seed);

  std::uniform_int_distribution<int> distribution(1,10);

  std::cout << "some random numbers between 1 and 10: ";
  for (int i=0; i<10; ++i)
    std::cout << distribution(generator) << " ";

  std::cout << std::endl;

  return 0;
}

Output

some random numbers between 1 and 10: 2 4 8 9 5 8 1 6 4 10


Second example

// uniform_int_distribution
#include <iostream>
#include <random>

int main()
{
  const int nrolls = 10000; // number of experiments
  const int nstars = 95;    // maximum number of stars to distribute

  std::default_random_engine generator;
  std::uniform_int_distribution<int> distribution(0,9);

  int p[10]={};

  for (int i=0; i<nrolls; ++i) {
    int number = distribution(generator);
    ++p[number];
  }

  std::cout << "uniform_int_distribution (0,9):" << std::endl;
  for (int i=0; i<10; ++i)
    std::cout << i << ": " << std::string(p[i]*nstars/nrolls,'*') << std::endl;

  return 0;
}

Output

uniform_int_distribution (0,9):
0: *********
1: *********
2: *********
3: *********
4: *********
5: *********
6: *********
7: *********
8: *********
9: *********