# Having some problem with a GCF program

• 08-08-2009
Requinex
Having some problem with a GCF program
So, I am new to C++ and only just started. I have bought a book called C++ Without Fear by Brian Overland, and I am having a problem with one of the exercises to do with the Greatest Common Factor.

The source code is:

Code:

```#include <iostream> using namespace std; int gcf(int a, int b); int main() {     int a = 0, b = 0;     while(1) {         cout << "Enter a number (0 to quit): ";         cin >> a;         if (a==0)         break;         cout << "Enter 2nd number: ";         cin >> b;         cout << "GCF = " << gcf(a, b) << endl;     }     return 0; } int gcf(int a, int b) {     if (a % b == 0)     return b;     else     return gcf(b, a % b);     cout << gcf(b, a % b); }```
That much I have managed to understand, but now after he explains it, he says to do an exercise where I revise the program so it shows all the steps involved in the algorithm.

For example-
GCF(300, 500) =>
GCF(500, 300) =>
GCF(300, 200) =>
GCF(200, 100) =>
GCF = 100

Right now, all that the code does is immediately give the answer.