Daily Archives: September 16, 2011

Random Number Generation with C++ 0x in GCC 2

This entry was posted in Practical Programming on by

In this post, I woud like to explore how random number would be generated by using newly added features from C++ 0x in GCC.

Rather than explaining the details of C++ 0x, I just post code here:

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#include <random>
#include <iostream>
#include <string>
#include <stdio.h>
#include <time.h>
 
using namespace std;
 
int main()
{
  int n;
  double p, lambda, shape, mu, sigma;
  mt19937 eng(time(NULL));
 
  uniform_int_distribution<int> uniform_int(3,7);
  for(int i=0; i < 10; i++)
    cout << "[Uniform INT distribution]:" << uniform_int(eng) << endl;
  cout << endl;
 
  uniform_real_distribution<double> uniform_real(0.0,1.0);
  for(int i=0; i < 10; i++)
    cout << "[Uniform REAL distribution]:" << uniform_real(eng) << endl;
  cout << endl;
 
  n = 5;
  p = 0.3;
  binomial_distribution<int> binomial(n, p);
  for(int i=0; i < 10; i++)
    cout << "[Binomial distribution]:" << binomial(eng) << endl;
  cout << endl;
 
  lambda = 4.0;
  exponential_distribution<double> exponential(lambda);
  for(int i=0; i < 10; i++)
    cout << "[Exponential distribution]:" << exponential(eng) << endl;
  cout << endl;
 
  shape = 3.0;
  gamma_distribution<double> gamma(shape);
  for(int i=0; i < 10; i++)
    cout << "[Gamma distribution]:" << gamma(eng) << endl;
  cout << endl;
 
  p = 0.5;
  geometric_distribution<int> geometric(p);
  for(int i=0; i < 10; i++)
    cout << "[Geometric distribution]:" << geometric(eng) << endl;
  cout << endl;
 
  mu = 3.0; sigma = 4.0;
  normal_distribution<double> normal(mu, sigma);
  for(int i=0; i < 10; i++)
    cout << "[Gaussian distribution]:" << normal(eng) << endl;
  cout << endl;
 
  lambda = 7.0;
  poisson_distribution<int> poisson(lambda);
  for(int i=0; i < 10; i++)
    cout << "[Poission distribution]:" << poisson(eng) << endl;
  cout << endl;
 
  p = 0.6;
  bernoulli_distribution bernoulli(p);
  for(int i=0; i < 10; i++)
    cout << "[Bernoulli distribution]:" << bernoulli(eng) << endl;
  cout << endl;
 
  return (0);
}

Note, the code is very clean in the sense that you don’t need any extra libraries at all.

Please compile with:

g++ -std=gnu++0x

The GCC I used is GCC 4.6.1

Several references:
1. http://www.johndcook.com/test_TR1_random.html (sort of out-dated)
2. http://www.johndcook.com/cpp_TR1_random.html (sort of out-dated)
3. http://gcc.gnu.org/onlinedocs/libstdc++/manual/status.html#status.iso.200x (current status of C++ 0x in GCC)
4. http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt01ch03s02.html ( a list of header files of C++ in GCC)