#include<stdio.h>
#include<stdlib.h>
int gcd(int, int);
int lcm(int, int);
int menu()
{
	int select;
	printf("**********************************\n");
	printf("*  1. 求兩數之最大公因數         *\n");
	printf("*  2. 求兩數之最小公倍數         *\n");
	printf("*  0. 結束程式                   *\n");
	printf("**********************************\n");
	printf("請輸入選項: ");
	scanf_s("%d", &select);
	return select;
}

int main()
{
	int select;
	int num1, num2,result;
	while (1)
	{
		select = menu();
		switch (select)
		{
		if (select == 0)
		{
			break;
		 }
		case 1:

			printf("======求兩數之最大公因數========\n");
			printf("請輸入兩整數:");

			int gcd();
			scanf_s("%d %d", &num1, &num2);
			result = gcd(num1, num2);
			printf("(%d,%d)=%8d\n\n", num1, num2,result);
			break;
		case 2:

			printf("======求兩數之之最小公倍數========\n");
			printf("請輸入兩整數:");

			int lcm();
			scanf_s("%d %d", &num1, &num2);
			printf("[%d,%d]=%8d\n\n", num1, num2, lcm(num1, num2));
			break;
		default:
			printf("輸入錯誤，請重新輸入");
			break;
		}

	}
	system("pause");
}
int gcd(int num1,int num2)
{
	int temp;
	while (num1%num2 != 0)
	{
		temp = num1%num2;
		num1 = num2;
		num2 = temp;
	}
	return num2;
}

int lcm(int num1,int num2)
{
	return num1*num2 / gcd(num1, num2);
}