<?php <BR>session_start(); <BR>$_SESSION['username']="zhuzhao"; <BR>?><BR>
<?php <BR>session_start(); <BR>unset($_SESSION['username']); <BR>if(isset($_SESSION['username']))<strong>)本文来(源gaodai#ma#com搞@@代~&码*网2</strong><pre>搞代gaodaima码
echo “username已经存在”;
else
echo “username不存在”;
?>