小学生四则运算小程序

#include<stdio.h>
#define N 120
#include<stdlib.h>
#include<math.h>

main()
{
    int num1,num2,answer,ranswer,a,b,c,operation,t;
    srand(time(NULL));
    a=rand()%3+1;
    b=rand()%3+1;
    c=rand()%4+1;
        switch(a)
    {
    case 1:
        a=10;
        break;
    case 2:
        a=100;
        break;
    case 3:
        a=1000;
    }
    switch(b)
    {
    case 1:
        b=10;
        break;
    case 2:
        b=100;
        break;
    case 3:
        b=1000;
    }
    num1=rand()%a;
    num2=rand()%b;
    switch(c)
    {
    case 1:
        operation=‘+‘;
        ranswer=num1+num2;
        break;
    case 2:
        operation=‘-‘;
        ranswer=num1-num2;
        break;
    case 3:
        operation=‘*‘;
        ranswer=num1*num2;
        break;
    case 4:
        operation=‘/‘;
        if(num2==0)
        {
            num2=1;
        }
        num1=num1*num2;    
        ranswer=num1/num2;
        break;
    }

    printf("%d%c%d=?\n",num1,operation,num2);
    while(answer!=ranswer)
    {
        scanf("%d",&answer);
        if(answer==ranswer)
            printf("恭喜你答对了!\n");
        else
            printf("你答错了，请重新再答!\n");
    }

}