随机生成30道四则运算题NEW

代码：

 #include <iostream>
 #include <time.h>
 using namespace std;

 void main()
 {
     srand((int)time(NULL));     //每次执行种子不同，生成不同的随机数
     int a, b, c, d, e, i, mark,opt;
     for (i = ; i < ; i++)
     {
         opt =  + rand() % ;//随机生成1或者2来表示整数和真分数
         a =  + rand() % ;//将1到100内的数随机赋予a
         b =  + rand() % ;//将1到100内的数随机赋予b
         c =  + rand() % ;//将1到100内的数随机赋予c
         d =  + rand() % ;//将1到100内的数随机赋予d
         if (opt == )
         {
             mark =  + rand() % ;//随机生成1-4来分别表示四个运算符
             cout << a;
             switch (mark)
             {
             case :cout << "+"; break;
             case :cout << "-"; break;
             case :cout << "×"; break;
             case :cout << "÷"; break;
             }
             cout << b << "=" << endl;
         }
         if (opt == )
         {
             if (a > b)
             {
                 e = a;
                 a = b;
                 b = e;
             }
             cout << "(" << a << "/" << b <<")";
             mark =  + rand() % ;
             switch (mark)
             {
             case :cout << "+"; break;
             case :cout << "-"; break;
             case :cout << "×"; break;
             case :cout << "÷"; break;
             }
             if (c > d)
             {
                 e = c;
                 c = d;
                 d = e;
             }
             cout << "(" << c << "/" << d << ")" <<"="<< endl;
         }

     }
 }