C++ Program on Euclid's algorithm

#include <iostream.h>
   // Fundamental idea of Euclid's algorithm (one of the oldest known algorithms)
   // gcd(a,0) = a
   // gcd(a,b) = gcd(b,a%b)
   int gcd (int a, int b)
   {
     int temp;
     while (b != 0)
     {
       temp = a % b;
       a = b;
       b = temp;
     }
     return(a);
   }
   int main ()
   {
     int x, y;
     cout << "Enter two natural numbers: ";
     cin >> x >> y;
     cout << "gcd(" << x << ", " << y << ") = " << gcd(x,y) << endl;
     return(0);
   }