小学生100以内加减运算

程序随机产生2个100以内运算数a和b，并随机产生一个运算（+、-），小学生计算并输入结果，程序应该显示运算式子，并给出小学生运算是否正确的判断信息

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main(int argc, char *argv[])
{
    int a, b, operation, ret;

    while(1){
        srand(time(NULL));
        a = rand() % 101;
        b = rand() % 101;
        operation = rand() % 2;
        ret = 0;
        if (operation){
            printf("%d + %d = ", a, b);
        }else {
            printf("%d - %d = ", a, b);
        }
        scanf("%d", &ret);
        if (operation){
            if (a + b == ret){
                printf("Correct.\n");
            }else {
                printf("False.\n");
            }
        }else {
            if (a - b == ret){
                printf("Correct.\n");
            }else {
                printf("False.\n");
            }
        }
        printf("-------------------------\n");
    }
    return 0;
}