C++ da modf() Metodun Kullanımı

//www.ethemsulan.com
#include <cstdlib>
#include <iostream>
#include <cmath>
using namespace std;
void run(double &num){
     double frac;
     double val;
     frac=modf(num,&val);
     if(frac<0.5) num=val;
     else num=val+1.0;
     }
int main(int argc, char *argv[])
{
    double i=100.4;
    cout<<i<<"'nin yuvarlatmisi: ";
    run(i);
    cout<<i<<endl;
    i=10.9;
    cout<<i<<"'nin yuvarlatmisi: ";
    run(i);
    cout<<i<<endl;
    system("PAUSE");
    return EXIT_SUCCESS;
}