#include <stdio.h>
#include <stdlib.h>

void title(){
	printf("=====欢迎使用czb的计算系统=====\n\n");
	printf("【1】加法运算\n");
	printf("【2】减法运算\n");
	printf("【3】乘法运算\n");
	printf("【4】除法运算\n");
	printf("【0】退出\n\n");
	return;
}

void exec(int mode){
	printf("输入第一个数：");
	int a;
	scanf("%d", &a);
	int b;
	while(1){
		printf("输入第二个数：");
		scanf("%d", &b);
		if(b != 0 || mode == 1 || mode == 2 || mode == 3) break;
	}
	int c;
	if(mode == 1) c = a + b;
	if(mode == 2) c = a - b;
	if(mode == 3) c = a * b;
	if(mode == 4) c = a / b;
	printf("结果是：%d\n\n", c);
	return;
}

void quit(){
	printf("真的要退出吗？(y/n)");
	char input;
	scanf("%c", &input);
	scanf("%c", &input);
	if(input == 'n' || input == 'N'){
		return;
	}else{
		exit(0);
	}
}

int main(){
	title();
	while(1){
		printf("输入您的选择：");
		int input;
		scanf("%d", &input);
		if(input == 0) quit();
		if(input == 1) exec(1);
		if(input == 2) exec(2);
		if(input == 3) exec(3);
		if(input == 4) exec(4);
	}
	return 0;
}