2、利用函数编程实现小学生四则运算练习系统。要求现在： (1)带菜单，循环使用 (2)菜单及加减乘除功能由函数实现 (3)自动判断对错并计算成绩

/*2、利用函数编程实现小学生四则运算练习系统。要求现在：
(1)带菜单，循环使用
(2)菜单及加减乘除功能由函数实现
(3)自动判断对错并计算成绩
*/
#include<iostream>
#include<iomanip>
#include<cmath>
#include<cstdlib>
#include<ctime>
using namespace std;
int gong_ti = 0;
int da_duei = 0;
int da_cuo = 0;
void Jei_mian(){
    int a;
    cout << "----------------------------------------------"<<endl;
    cout << "输入选择(1--5):";
}
             //加法
void Jiafa() {
        cout <<"\t\t第"<< gong_ti+1 <<"题"<<endl;
    int a, b;
    int daan;
    gong_ti++;
    srand(time(0));
    a = rand() & (100 - 1 + 1) + 1;
    b = rand() & (100 - 1 + 1) + 1;
    cout << a << '+' << b << '=';
    cin >> daan;
    if (a + b == daan) {
        cout << "你的答案对了"<<endl;
        da_duei++;
    }
    else {
        cout << "你的答案错了" << endl
            << "正确答案是:"
            << a << '+' << b << '=' << a + b << endl;
        da_cuo++;
    }
}  
             //减法
void Jianfa() {
        cout <<"\t\t第"<< gong_ti+1 <<"题"<<endl;
    int a, b;
    int daan;
    gong_ti++;
    srand(time(0));
    a = rand() & (100 - 1 + 1) + 1;
    b = rand() & (100 - 1 + 1) + 1;
    cout << a << '-' << b << '=';
    cin >> daan;
    if (a - b == daan) {
        cout << "你的答案对了" << endl;
        da_duei++;
    }
    else {
        cout << "你的答案错了" << endl
            << "正确答案是:"
            << a << '-' << b << '=' << a - b << endl;
        da_cuo++;
    }
}
             //乘法
void chengfa() {
        cout <<"\t\t第"<< gong_ti+1 <<"题"<<endl;
    int a, b;
    int daan;
    gong_ti++;
    srand(time(0));
    a = rand() & (100 - 1 + 1) + 1;
    b = rand() & (100 - 1 + 1) + 1;
    cout << a << '*' << b << '=';
    cin >> daan;
    if (a * b == daan) {
        cout << "你的答案对了" << endl;
        da_duei++;
    }
    else {
        cout << "你的答案错了" << endl
            << "正确答案是:"
            << a << '*' << b << '=' << a - b << endl;
        da_cuo++;
    }

}
             //除法
void chufa() {
        cout <<"\t\t第"<< gong_ti+1 <<"题"<<endl;
    int a, b;
    int daan;
    gong_ti++;
    srand(time(0));
    a = rand() & (100 - 1 + 1) + 1;
    b = rand() & (100 - 1 + 1) + 1;
    cout << a*b << '/' << b << '=';
    cin >> daan;
    if (daan == a) {
        cout << "你的答案对了" << endl;
        da_duei++;
    }
    else {
        cout << "你的答案错了" << endl
            << "正确答案是:"
            << a * b << '/' << b << '=' << a << endl;
        da_cuo++;
    }

}

int main() {
    int a;
    bool b= true;
    cout << "\t\t" << "************************" << endl
         << "\t\t" << "**--------------------**" << endl
         << "\t\t" << "**--四则运算练习系统--**" << endl
         << "\t\t" << "**--------------------**" << endl
         << "\t\t" << "************************" << endl
         << "\t\t" << "**+------1.加法------+**" << endl
         << "\t\t" << "************************" << endl
         << "\t\t" << "**+------2.减法------+**" << endl
         << "\t\t" << "************************" << endl
         << "\t\t" << "**+------3.乘法------+**" << endl
         << "\t\t" << "************************" << endl
         << "\t\t" << "**+------4.除法------+**" << endl
         << "\t\t" << "************************" << endl
         << "\t\t" << "**+++--------------+++**" << endl
         << "\t\t" << "**+++----5.退出----+++**" << endl
         << "\t\t" << "**+++--------------+++**" << endl
         << "\t\t" << "************************" << endl;
    while (b== true) {
        Jei_mian();
        cin >> a;
        switch (a) {
        case 1:
            Jiafa();
            break;
        case 2:
            Jianfa();
            break;
        case 3:
            chengfa();
            break;
        case 4:
            chufa();
            break;
        case 5:
            b = false;
            break;
        }
    }
    if (gong_ti != 0) {
        cout << "一共有" << gong_ti << "题,";
    }
    if (da_duei != 0) {
        cout << "答对" << da_duei << "题,";
    }
    if (da_cuo != 0) {
        cout << "答错" << da_cuo << "题.";
    }

    return 0;
}