<html>
<head>
<title>用户登录</title>
</head>
<body>
<?php
function getCookieUsername(){
 if(empty($_COOKIE['username'])){
  return "";
 }else{
  return $_COOKIE['username'];
 }
}
?>
<form action="admin.php" method="post">
用户名：<input type="text" name="username" value="<?php echo getCookieUsername(); ?>"><br />
密码：<input type="password" name="pwd"><br />
是否保存用户名：<input type="checkbox" name="yes"><br />
<input type="submit" name="sub" value="登录">
</form>
</body>
</html>

<?php
if(!empty($_POST['sub']) && $_POST['username']=="admin"){
 echo "欢迎".$_POST['username']." 登录成功";
 if(!empty($_POST['yes'])){
  setCookie("username",$_POST['username'],time()+3600*24*30);
 }else{
  setCookie("username","",time()-10);
 }
}else{
 echo "你的账号错误，请重新输入<br />";
}
echo "<a href='login.php'>返回登录页面</a>";
?>