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 == )
             throw ;
         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==)
             throw int();
         if(e2==)
             throw long();

         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;
         }
 }