Question

When I run this code is just hangs in for loop, can you explan why?

#include<iostream>
#include<random>
#include<ctime>

int main()
{
    using std::cout;
    using std::endl;
    using std::cin;
    using std::mt19937;
    using std::minstd_rand;
    using std::uniform_int;
    using std::normal_distribution;

    // engines
    mt19937 rng;
    minstd_rand gen;

    // distributions
    uniform_int<int> dist(0, 37);
    normal_distribution<short> norm(4, 3);

    // initializaiton
    rng.seed(static_cast<unsigned int>(time(false)));
    gen.seed(static_cast<unsigned short>(time(false)));



    // generate numbers
    for(int i = 0; i < 10; ++i)
        std::cout << dist(rng) << "     " << norm(gen) << endl; // This is as far as this code goes

    cin.get();
    return 0;
}

Answer 1

std::uniform_int is not C++11. You should use std::uniform_int_distribution. And std::normal_distribution<T> requires T to be floating point type (C++11 standard 26.5.8.5.1).

In fact, if you have gcc >= 4.5 you should get an error saying something like:

/opt/local/include/gcc47/c++/bits/random.h: In instantiation of 'class std::normal_distribution<short int>':
my_random.cpp:21:36:   required from here
/opt/local/include/gcc47/c++/bits/random.h:1982:7: error: static assertion failed: template argument not a floating point type