#include

#include

#define U 30

struct users

{

char ac[30];

char pw[30];

}

;

struct users use[U];//结构体

void wel();

void registeruser();

void login();

void userview();

void main()

{

wel();

}

void wel()

{

char se;

while ( se != '3' )

{

system( "cls" );

printf( "按1-注册-" );

printf( "\n" );

printf( "按2-登录-" );

printf( "\n" );

printf( "按3-退出-" );

printf( "\n" );

printf( "选择：" );

scanf( "%s", &se );

switch ( se )

{

case '1':

registeruser();

break;

case '2':

login();

break;

case '3':

exit( 0 );

break;

default:

if ( se != '1' || se != '2' || se != '3' )

printf( "没有这个选项!\n" );

system( "pause" );

break;

}

}

}

void registeruser()

{

charac[30];

charpw[30];

inta = 0;

printf( "\t以下为注册帐号\n" );

FILE *fp;

fp = fopen( "c:\\user", "a" );//写入文件操作

if ( fp == NULL )

{

printf( "没有帐号信息..." );

printf( "\n" );

return;

}

printf( "请输入帐号:" );

scanf( "%s", &ac );

printf( "请输入密码:" );

scanf( "%s", &pw );

strcpy( use[a].ac, ac );

strcpy( use[a].pw, pw );

fprintf( fp, "%s %s\n", use[a].ac, use[a].pw );

fclose( fp );

printf( "已注册..." );

printf( "\n" );

system( "pause" );

}

void login()

{

charac[30];

charpw[30];

inta= 0;

intflag= 0;

printf( "\t以下为登录帐号\n" );

printf( "请输入帐号:" );

scanf( "%s", &ac );

printf( "请输入密码:" );

scanf( "%s", &pw );

FILE *fp;

fp = fopen( "c:\\user", "r" );//读取文件操作

while ( !feof( fp ) )

{

fscanf( fp, "%s %sn", &use[a].ac, &use[a].pw );

if ( (strcmp( ac, use[a].ac ) == 0) && (strcmp( pw, use[a].pw ) == 0) )

{

flag = 1;

fclose( fp );

break;

}

a++;

}

if ( flag == 1 )

{

userview();

return;

}else{

printf( "帐号或者密码错误!\n" );

}

system( "pause" );

}

void userview()

{

int a = 0;

printf( "登录成功!" );

printf( "按任意键显示所有用户!\n" );

system( "pause" );

FILE *fp;

fp = fopen( "c:\\user", "r" );//读取文件操作

while ( fscanf( fp, "%s %sn", &use[a].ac, &use[a].pw ) != EOF )

{

printf( "\t帐号:%s 密码:%s\n", use[a].ac, use[a].pw );

a++;

}

fclose( fp );

system( "pause" );

}

注册后会在C盘增加一个存用户名的user文件

运行如图；

选择错误时

注册

登录成功并显示文件内容

登录失败