C++初学（1） 简单的加减乘除取余运算代码

//---------------+-*/%算法----------------------------------------------------------
#include <iostream>
using namespace std;
// 函数原型声明
int Add(int e1, int e2);
int Sub(const int*pe1, const int*pe2);
int Mul(const int&re1, const int&re2);
int Div(int e1, int e2)throw(int); // 分母不能为0，否则抛出除0错
int Mod(int e1,int e2)throw(int,long); //分子 分母不能为0，否则抛出无意义错或除0错

void main() {
    int e1, e2, result;
    char optr;

    while (true) {
        cout <<
        "Please type in an expression which likes a @b,type 'q' to quit" << endl;
        cin >> optr;
        if (optr == 'q' || optr == 'Q')
            break; // 结束循环
        cin.putback(optr); // 将读入的字符退回到流中，让它可以被重新读入
        cin >> e1;
        cin >> optr;
        cin >> e2;

        switch(optr) {
        case '+':
            result = Add(e1, e2);
            break;
        case '-':
            result = Sub(&e1, &e2);
            break;
        case '*':
            result = Mul(e1, e2);
            break;
        case '/':
            result = Div(e1, e2);
            break;
        case '%':
            result = Mod(e1, e2);
            break;
        }
    }
    system("pause");
}

int Add(int e1, int e2) {
    int result = e1 + e2;
    cout << '=' << result << endl;
    return result;
}

int Sub(const int *pe1, const int *pe2) {
    int result = *pe1 - *pe2; // 指针指向的内存地址里面存的数值相减
    cout << '=' << result << endl;
    return result;
}

int Mul(const int &re1, const int &re2) {
    int result = re1 * re2;
    cout << '=' << result << endl;
    return result;
}

int Div(int e1, int e2)throw(int) {
    try {
        if (e2 == 0)
            throw 0;
        int result = e1 / e2;
        cout << '=' << result << endl;
        return result;
    }
    catch(int) {
        cout << "Denominator cannot be zero" << endl;
    }

}

 int Mod(int e1,int e2)throw(int,long)
{
    try
    {
        if(e1==0)
            throw int(0);
        if(e2==0)
            throw long(0);

        int result=e1%e2;
        cout << '=' << result << endl;
        return result;
    }
        catch(int)
        {
        cout<<"It doesn't make sense when numerator is zero"<<endl;
        }
        catch(long)
        {
        cout<<"Denominator cannot be zero"<<endl;
        }
}