#include <stdio.h>
#include <stdlib.h> 
void displayMenu()
{
    system("cls");
    printf("       欢迎进入计算器\n ");
    printf("***************************\n ");
    printf("*          1.加法         *\n ");
    printf("*          2.减法         *\n ");
    printf("*          3.乘法         *\n ");
    printf("*          4.除法         *\n ");
    printf("*          5.求余         *\n ");
    printf("*          6.阶乘         *\n ");
    printf("*          7.累加         *\n ");
    printf("*          8.结束         *\n ");
    printf("***************************\n ");
    printf("请输入计算类型编号:");
}
int function(int e)
{
    if (e == 1 || e == 0)
        return 1;
    else
        return e * function(e - 1);
}
int main()
{
    char user, y;
    int input, a = 0, b = 0;
    printf("是否进入计算器,y/n(是/否):");
    scanf("%c", &user);
    if (user == 'y')
        displayMenu();
    else if (user == 'n') 
        exit(0);         
    else
    {
        printf("输入有误,请重新输入");
        exit(0);
    }
    scanf("%d", &input); //接收计算类型参数
    system("cls");
    switch (input)
    {
    case 1:
    {
        printf("请输入数据:");
        scanf("%d%d", &a, &b);
        printf("%d+%d=%d\n", a, b, a + b);
        break;
    }
    case 2:
    {
        printf("请输入数据:");
        scanf("%d%d", &a, &b);
        printf("%d-%d=%d\n", a, b, a - b);
        break;
    }
    case 3:
    {
        printf("请输入数据:");
        scanf("%d%d", &a, &b);
        printf("%d*%d=%d\n", a, b, a * b);
        break;
    }
    case 4:
    {
        printf("请输入数据:");
        scanf("%d%d", &a, &b);
        printf("%d/%d=%d\n", a, b, a / b);
        break;
    }
    case 5:
    {
        printf("请输入数据:");
        scanf("%d%d", &a, &b);
        printf("%d mold %d=%d\n", a, b, a % b);
        break;
    }
    case 6:
    {
        int e = 0;
        printf("请输入数据:");
        scanf("%d", &e);
        printf("%d!=%d\n", e, function(e));
        break;
    }
    case 7:
    {
        int result = 0;
        for (int i = 0; i < 1000; i++)
        {
            char input1;
            printf("退出请按任意键,计算请按M键:"); 
            scanf("%s", &input1);
            if (input1 == 'M' || input1 == 'm')
            {
                int c, d;
                printf("请输入数据:");
                scanf("%d%d", &c, &d);
                printf("result=%d\n", result += (c + d)); 
            }
            else
                exit(0);
        }
        break;
    }
    case 8:
    {
        printf("谢谢使用,再见!");
        exit(0);
        break;
    }
    default:
        printf("error,please try again!!!");
    }
    system("pause");
    return 0;
}