<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=utf8" />
</head>
<body>
<form method="post" action="login.php">
用户:<input type="text" name="username" />
<input type="submit" value="提交" />
</form>
</body>
</html>

<?php
if($_POST['username'] = 'admin')
{
setcookie('haha','gogo');
header("location:index.php");
}
?>

<?php
if($_COOKIE['haha'] == 'gogogo')
{
echo $_COOKIE['haha'];
echo'你设置了cookie';
}
else
{
echo'你没有设置cookie';
}
?>