php session_start()出錯原因分析及解決方法

錯誤提示： Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent

原因：在session_start()之前如果有輸出內容，會出錯，

解決辦法：在session_start()之前加上ob_start();

index.php 
復制代碼 代碼如下:
<?php
error_reporting(-1);
ob_start();//不加會出錯，無法寫入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>

index2.Php
復制代碼 代碼如下:
<?php
error_reporting(-1);
ob_start();//不加會出錯，無法讀取session
?
echo 1;
 session_start();

echo $_SESSION['password'];
var_dump($_SESSION);
?>
<a href="index.php" >index</a>