c++ Greatest common divisor

The greatest common divisor (GCD) of two integers is the largest integer that evenly divides each of the numbers. Write a function gcd that returns the greatest common divisor of two integers.

Example 

#include <iostream>
using namespace std;
int gcd( int, int );
int main()
{
int a, b;
for ( int j = 1; j <= 5; ++j ) {
cout << "Enter two integers: ";
cin >> a >> b;
cout << "The greatest common divisor of " << a << " and "<< b << " is " << gcd( a, b ) << "\n\n";
}
return 0;
}
int gcd( int x, int y )
{

int greatest = 1;
for ( int i = 2; i <= ( ( x < y ) ? x: y ); ++i )
if ( x % i == 0 && y % i == 0 )
greatest = i;
return greatest;
}