程序代码：

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

typedef
struct{
char name[10];
char ps[10];
int power;
}Student;

int main(){
   FILE *fp=fopen("date.dat","wb");
   Student show1[2]={{"tea","tea123",1},{"stu","stu123",0}};
   Student tmps,show;
   char temp;

   char datafile[]="student",relogin;
  int i,success=0;


  if(fp!=NULL){
    fwrite(show1,sizeof(Student),2,fp);
    fclose(fp);
}
  printf("================================================\n");
  printf(" 欢  迎  进  入  学  生  请  假  管  理  系  统\n");
  printf("================================================\n");

again:
      printf("请输入用户名：");
     scanf("%s",tmps.name);
printf("请输入密码：");

while ((temp= getch ()) != '\r') {
  putchar ('*');

 tmps.ps[i++]=temp;
}
if(tmps.ps[i-1]==' ')

 tmps.ps[i-1]='\0';
    else
  tmps.ps[i]='\0';


 fp=fopen("date.dat","rb");
   if(fp==NULL){
        printf("文件%s打不开\n",datafile);
   exit(1);
}

 while(fread(&show,sizeof(Student),1,fp)!=0) {
    if((strcmp(tmps.name,show.name)==0)&&(strcmp(tmps.ps,show.ps)==0))
        printf("登录成功!\n");
    success=1;
    if(show.power==1){
        printf("您是老师！");


    }
    if(show.power==0){
        printf("你是学生！");

            }
            fclose(fp);


 }


 if(success==0) {
    printf("\n您输入的名字或密码有误，是否重新输入?(y/n)");

    relogin=getche();

    if((relogin=='y')||(relogin=='Y')) {


        printf("请再次输入名字和密码\n");

        goto again;
    }
    else
    {
    printf("程序结束");
    exit(0);
    }

}return 0;
}