错误提示： Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent
原因：在session_start()之前如果有输出内容，会出错，
解决办法：在session_start()之前加上ob_start();
index.php
<?php
error_reporting(-1);
ob_start();//不加会出错，无法写入session
register_shutdown_function('close');
echo 1;
session_start();
$_SESSION['password']='mima2ddddddddddddddda2';
function close()
{
if(session_id()!=='')
@session_write_close();
}
?>
<a href="index2.php" >index2</a>
<?php
error_reporting(-1);
ob_start();//不加会出错，无法读取session
?
echo 1;
session_start();
echo $_SESSION['password'];
var_dump($_SESSION);
?>
<a href="index.php" >index</a>
