Here's a program that will ask for two numbers then give the greatest common factor.

Source Code:
Code:
#include <iostream.h>

void GCF(int x, int y)
{
     int z, l=1;//i'm setting l and will use it as a loop
     z=y+1;
     
     while(l!=0)//keep looping until l is 0, which it wont be, unless common factors are found
     {
          z--; //subtracts from number
          
          if(y%z == 0 && x%z == 0) // if remainders equal zero, set l to zero, so it can display that number
          {
                 l=0;
          }
     }
     cout<<"The GCF is: "<<z<<endl; //z is now the GCF
}
int main()
{
    int x, y;
    
    cout<<"Enter a number: ";
    cin>>x;
    cout<<"Enter another number: ";
    cin>>y;
    if(x>y)  //if and else statements take care of different inputs, and call the void function above.
    {
           GCF(x, y);
    }
    else
    {
        GCF(y, x);
    }
    
    system ("PAUSE");
    return 0;
}