四则运算

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
int a[100],b[100];
char c[100],sym[4]={'+','-','*','/'};
int answer(int i);
void printanswer(int n);
void main()
{
    int n,o,count;
    int i;
    char r;
       srand((unsigned)time(NULL));
        while(1)
        {
            count=0;
            printf("输入需要的题目数(0退出)：");
            scanf("%d",&n);
            if(n==0) exit(0);
            for(i=0;i<n;i++)
            {
            a[i]=rand()%101;
            b[i]=rand()%101;
            c[i]=sym[rand()%4];
            printf("%d%c%d=",a[i],c[i],b[i]);
            scanf("%d",&o);
            if(o==answer(i)) {
                printf("正确!\n");
                count++;
            }
            else printf("错误!答案是%d\n",answer(i));
            }
            printf("答对了%d题\n",count);
        }
}
int answer(int i)
{
    int o;
        if(c[i]==sym[0]) o=a[i]+b[i];
        if(c[i]==sym[1]) o=a[i]-b[i];
        if(c[i]==sym[2]) o=a[i]*b[i];
        if(c[i]==sym[3]) o=a[i]/b[i];
        return o;
}