给小学生出20以内加减法运算题

Question

Answer 1

代码如下：

#include <stdio.h>
#include <time.h>
#include <stdlib.h>
int main()
{
    int a,b,c,res,i,t;
    int cnt = 0;
    
    srand((unsigned int)time(NULL));
    for (i=0;i<10;i++)
    {
        c = rand()%2; //生成0-1的随机数
        if(c == 0)
        {
            a = rand()%20;//生成0-19的随机数
            b = rand()%(20-a);
            
            printf("%d + %d = ",a,b);
            scanf("%d",&res);
            if(res == a+b)
            {
                cnt++;
                printf("回答正确\n");
            }else
            {
                printf("回答错误\n");
            }
        }else
        {
            a = rand()%20;//生成0-19的随机数
            b = rand()%20; 
            if(a<b)
            {
                t = a;
                a = b;
                b = t;
            }
            printf("%d - %d = ",a,b);
            scanf("%d",&res);
            if(res == a-b)
            {
                cnt++;
                printf("回答正确\n");
            }else
            {
                printf("回答错误\n");
            }
        }
    }
    printf("得分：%d",cnt*10);
    return 0;
}