Functions Basic 2

#include <iostream.h>

double fact (int);
int main ()
{
    int a=0;
    cout <<"Enter Number : ";
    cin >> a;
    cout << fact (a);
    return 0;
}
double fact (int n)
{
    int counter=n;
    double factorial=1;
    while (counter>1)
    {
        factorial=factorial*counter;
        counter--;
    }
    return factorial;
}