// Program FactTest is a driver program that test function
// Factorial.                                     

#include <iostream>
using namespace std;

int  Factorial(int);

int main ()
{
    int  number;    

    cout  << "Enter a nonnegative integer number. "
	  << "Press return."  << endl;
    cin  >> number;
    while (number >= 0)
    {
	      cout  << number  << " factorial is "
	            << Factorial(number)  << endl;
	      cout  << "To continue, enter another nonnegative "
	            << "number; to quit, enter a negative number."
	            << endl;
	      cin  >> number;
    }
    return 0;
}

/********************************************************/
                                                            
int  Factorial(int  number)          
// The factorial of number is calculated iteratively.  
{
    int  tempFact = 1;
    while (number > 1)
    {
        tempFact = tempFact * number;
        number = number - 1;
    }
    return tempFact;
}