这个怎么编，求解答啊

rand（）%4+1产生1-4的随机整数，1-100：rand（）%100+1，很简单

#include <stdio.h>
#include <time.h>
#include <stdlib.h>
int main()
{
    srand((int)time(0));
    int m =rand()%100;
    int n =rand()%100;
    int k =rand()%4+1;
    printf("%d %d %d\n",m,n,k);
    double res;
    switch(k)
    {
        case 1:
            res=m+n;
            break;
        case 2:
            res=m-n;
            break;
        case 3:
            res=m*n;
            break;
        case 4:
            res=(double)m/n;
            break;
    }
    printf("%lf",res);
    return 0;
}