求教！！我只前没遇到过这个问题啊！！！

#include<stdio.h>#include<stdlib.h>#include<math.h>#include<string.h>#include<ctype.h>#include<windows.h>#include<time.h>
int main(){ char ID[7]; int validation=0; int judge(char []); int select,i,yunsuan,ysy1,ysy2,result,ans,zq,cw; zq=0; cw=0; while(validation==0) { printf("请输入您的ID号码"); gets(ID); validation=judge(ID); if(validation=0) { printf("无效的ID号码"); } } printf("输入1开始测试"); printf("输入2查看历史成绩"); printf("输入3推出"); scanf("%d",&select); switch(select) { case 1: for (i=1;i<=10;i++)//进行十次运算 { yunsuan=1+rand()%4;//随机选择运算类型 switch(yunsuan) { case 1://加法 ysy1=100; ysy2=100; while(ysy1+ysy2>100) { ysy1=0+rand()%101; ysy2=0+rand()%101; } result=ysy1+ysy2; printf("%d+%d=",ysy1,ysy2); scanf("%d",ans); if(ans==result) zq++; else cw++; case 2://减法 ysy1=1; ysy2=100; while(ysy1<ysy2) { ysy1=0+rand()%101; ysy2=0+rand()%101; } result=ysy1-ysy2; printf("%d-%d=",ysy1,ysy2); scanf("%d",ans); if(ans==result) zq++; else cw++; case 3://乘法 ysy1=100; ysy2=100; while(ysy1*ysy2>100) { ysy1=0+rand()%101; ysy2=0+rand()%101; } result=ysy1*ysy2; printf("%d*%d=",ysy1,ysy2); scanf("%d",ans); if(ans==result) zq++; else cw++; case 4://除法 ysy1=100; ysy2=100; while((ysy1*ysy2>100)&&(ysy1%ysy2)!=0&&(ysy1<ysy2)) { ysy1=0+rand()%101; ysy2=0+rand()%101; } result=ysy1/ysy2; printf("%d/%d=",ysy1,ysy2); scanf("%d",ans);