四则运算

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
int main()
{
  int x,y,m,i,t;
  srand(time(NULL)); //rand函数产生的是伪随机数，设置srand()函数使随机数改变
  for(i=0;i<300;i++)
    {   x=rand()%100;   //0~99             
        y=rand()%100;     
        m=rand()%4;
        switch(m)
        {
         case 0:
             printf("%d+%d=\n",x,y);
             break;
         case 1:
              if(x<y)
               {
                   t=x;
                   x=y;
                   y=t;
                }
              printf("%d-%d=\n",x,y);
         case 2:
             printf("%d*%d=\n",x,y);
         case 3:
              if(y!=0)
              printf("%d/%d=\n",x,y);
              else
                   i--;
           }
         }
       return 0;
     }
   运行结果：