~cpp 
#include <iostream>

using namespace std;

void main()
{
	int number_a, number_b;
	cout << "첫번째 숫자를 입력하세요:";
	cin >> number_a;
	cout << "두번째 숫자를 입력하세요:";
	cin >> number_b;
	cout << "\tx = " << number_a << "\ty = " << number_b << "\n";
	int *big_number, *small_number;
	if (number_a>number_b)
	{
		big_number=&number_a;
		small_number=&number_b;
	}
	else
	{
		big_number=&number_b;
		small_number=&number_a;
	}
	int temp;
	while (temp=*big_number%*small_number)
         {
		*big_number=*small_number;
		*small_number=temp;
         }
	cout << "\tGCD is " << *small_number << "\n";
}

~cpp 
#include <iostream>

using namespace std;

void get_GCM(int big_number, int small_number)
{
	int temp;
	while (temp=big_number%small_number)
         {
		big_number=small_number;
		small_number=temp;
         }
	cout << small_number << "\n";
}

void main()
{
	int number_a, number_b;
	cout << "첫번째 숫자를 입력하세요:";
	cin >> number_a;
	cout << "두번째 숫자를 입력하세요:";
	cin >> number_b;
	cout << "The GCD of " << number_a << " and " << number_b << " is ";
	if (number_a>number_b)
		get_GCM(number_a, number_b);
	else
		get_GCM(number_b, number_a);

}

~cpp 
#include <iostream>

using namespace std;

int Get_GCM(int , int );

void main()
{
	int number_a, number_b;
	cout << "첫번째 숫자를 입력하세요:";
	cin >> number_a;
	cout << "두번째 숫자를 입력하세요:";
	cin >> number_b;
	cout << "The GCD of " << number_a << " and " << number_b << " is "<< get_GCM(number_a,number_b) << "\n";
}

int Get_GCM(int number_a, int number_b)
{
	int temp;
	while (temp=number_a%number_b)
	{
		number_a=number_b;
		number_b=temp;
	}
	return number_b;
}