php中施用session

session_start(); $_SESSION['username'] = $username;

//验证sessionsession_start();//session中是否存在username并且session是否过期if(!isset($_SESSION["username"])|| time()";	echo '点击此处 <a href="login.html">登录</a> ！<br>';	exit;}

session_start();/*** 删除所有的session变量..也可用unset($_SESSION[xxx])逐个删除。****/$_SESSION = array();/***删除sessin id.由于session默认是基于cookie的，所以使用setcookie删除包含session id的cookie.***/if (isset($_COOKIE[session_name()])) {	setcookie(session_name(), '', time()-42000, '/');}// 最后彻底销毁session.session_destroy();//跳转到登陆页面Header("HTTP/1.1 303 See Other"); Header("Location: login.html");