#include<stdio.h>

#include<string.h>

#include<math.h>

#include<stdlib.h>

struct sysuser

{

 char username[20];

 char password[16];

};

int zhuce();

int CheckUserValid(struct sysuser *psu);

int main()

{

 printf("请注册账号\n");

 if(zhuce)

 printf("注册成功\n");

 struct sysuser su;

 printf("输入用户名\n");

 scanf("%s",su.username);

 printf("输入密码\n");

 scanf("%s",su.password);

 if(CheckUserValid(&su)==1)

 printf("登陆成功\n");

 else

 printf("账号或密码不正确\n");

}

int zhuce()//注册函数

{

 FILE *fp;

 struct sysuser su;//文件指针

 if((fp=fopen("user.txt","w"))==NULL)

 {

  printf("抱歉，没有指定文件");

     exit(0);

 }

 printf("请输入用户名\n");

 scanf("%s",su.username);

 printf("请输入密码\n");

 scanf("%s",su.password);

 fprintf(fp,"%s %s\n",su.username,su.password);

 fclose(fp);

 return 1;

}

int CheckUserValid(struct sysuser *psu)//登录函数

{

 FILE *fp;

 if((fp=fopen("user.txt","r"))==NULL)

 {

  printf("找不到指定文件");

  exit(0);

 }

 char use[32],rightUse[32],pass[16];

 int flag=0;

 strcpy(use,(*psu).username);

 strcpy(pass,(*psu).password);

 strcat(use," ");

 strcat(use,pass);

 strcat(use,"\n");

 while(!feof(fp))

 {

  fgets(rightUse,32,fp);

  if(strcmp(use,rightUse)==0)

  {

   flag=1;

   break;

  }

  if(fclose(fp))

  {

   printf("不能关闭这个文件");

   exit(0) ;

  }

 }

 return flag;

}