ob_get_level

(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

ob_get_level — 返回输出缓冲机制的嵌套级别

说明

ob_get_level(): int

返回输出缓冲机制的嵌套级别。

参数

此函数没有参数。

返回值

返回嵌套的输出缓冲处理程序的级别；或者是，如果输出缓冲区不起作用，返回零。

警告

ob_get_level() 和 ob_get_status() 之间相同级别的值相差 1。对于 ob_get_level()，第一级为 1。而对于 ob_get_status()，第一级为 0。

参见

ob_start() - 打开输出控制缓冲
ob_get_status() - 得到所有输出缓冲区的状态
ob_get_contents() - 返回输出缓冲区的内容

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用户贡献的备注 3 notes

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Anonymous ¶

12 years ago

For users confused about getting "1" as a return value from ob_get_level at the beginning of a script: this likely means the PHP ini directive "output_buffering" is not set to off / 0. PHP automatically starts output buffering for all your scripts if this directive is not off (which acts as if you called ob_start on the first line of your script).

If your scripts may end up on any server and you don't want end-users to have to configure their INI, you can use the following at the start of your script to stop output buffering if it's already started:
<?php
if (ob_get_level()) ob_end_clean();
?>

Alternatively, you can use the opposite if you always want to have an output buffer at the start of your script:
<?php
if (!ob_get_level()) ob_start();
?>

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Anonymous ¶

9 years ago

This can be used to handle exceptions properly when using output buffering for rendering a view which may or may not be using output buffering

<?php

function getView($view)
{
    $level = ob_get_level();
 
    ob_start();
 
    try
    {
        include $view;
    }

    catch (Exception $e)
    {
        while (ob_get_level() > $level)
        {
            ob_end_clean();
        }

        throw $e;
    }

    return ob_get_clean();
}

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bonzini at gnu dot org ¶

20 years ago

Even under older PHP, you can decide if output buffering is active (i.e. ob_get_level() > 0) using



   <?php $ob_active = ob_get_length () !== FALSE ?>



Paolo