#include "stdio.h"
#include "stdlib.h"
#include "time.h"

int f1(int x,int y,int z);
main()
{
    int x,y,z;
    srand(time(NULL));
    x=rand()%100;
    y=rand()%100;
    z=x+y;
    int f1(x,y,z);
}
int f1(int x,int y,int z)
{
   int i,m;

   for(i=1;i<=3;i++)
     {
     printf("%d+%d=?\n",x,y);
     scanf("%d",&m);

      if(m==z)
            {
           printf("Right!");
            break;
         }
      else if(m!=z)
                {
           printf("NOT corect! try again!");
            }
      }
    printf("not correct ,you have tried three times! Test over!");
    return 0;
}

那什么情况下可以定义函数类型