The definition should mention that the function also "turns off output buffering", not just cleans it.
(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)
ob_get_clean — アクティブな出力バッファの内容を取得し、そのバッファをオフにする
この関数は、
(PHP_OUTPUT_HANDLER_CLEAN と
PHP_OUTPUT_HANDLER_FINAL フラグを指定して)
出力ハンドラをコールし、その戻り値を破棄するとともに、
アクティブな出力バッファの内容を返しつつ、
かつそれをオフにします。
PHP_OUTPUT_HANDLER_REMOVABLE を指定して
アクティブな出力バッファを開始しないと、
ob_get_clean() は失敗します。
ob_get_clean()
は、PHP_OUTPUT_HANDLER_CLEANABLE
を指定せずにアクティブな出力バッファを開始したとしても、
そのバッファの内容をクリアします。
この関数にはパラメータはありません。
成功した場合、アクティブな出力バッファの内容を返します。
失敗した場合は、false を返します。
この関数が失敗すると、
E_NOTICE が発生します。
例1 単純な ob_get_clean() の例
<?php
ob_start();
echo "Hello World";
$out = ob_get_clean();
$out = strtolower($out);
var_dump($out);
?>上の例の出力は以下となります。
string(11) "hello world"
The definition should mention that the function also "turns off output buffering", not just cleans it.Also, don't forget that you will need to ob_start() again for any successive calls:
<?php
ob_start();
echo "1";
$content = ob_get_clean();
ob_start(); // This is NECESSARY for the next ob_get_clean() to work as intended.
echo "2";
$content .= ob_get_clean();
echo $content;
?>
Output: 12
Without the second ob_start(), the output is 21 ...Keep in mind that output may be buffered by default, depending on how you are running PHP (CGI, CLI, etc.). You can use ob_get_level() to determine if an output buffer has already been started. On most web servers I've used, output buffering is already one level deep before my scripts start running.
You should only end as many output buffers as you start. Assuming that your buffer is always the first buffer, or otherwise closing pre-existing buffers, could lead to problems. In PHP 5.5, you can ensure that output buffers are ended properly using a try-finally block.
Something like this is almost guaranteed to break stuff:
<?php
// Don't ever do this!
while (ob_get_level() > 1)
{
ob_end_flush();
}
$content = ob_get_clean();
?>
The problem is that number, "1". Using a fixed number there is asking for trouble. Instead, use ob_get_level() to get the number of output buffers applied when your code starts, and return to that number, if you really must use an unknown number of output buffers:
<?php
ob_start();
$saved_ob_level = ob_get_level();
// Do stuff here:
run_something();
// If you really must close all of your output buffers except one, this'll do it:
while (ob_get_level() > $start_ob_level)
{
ob_end_flush();
}
// And now, the final output buffer that belongs to us:
$content = ob_get_clean();
?><?php
ob_start();
echo "1";
$content = ob_get_clean();
echo "2";
$content .= ob_get_clean();
echo $content;
?>
This script outputs 21 in CLI mode and 12 otherwise (under my apache and nginx)I was trying to debug my code using error_log() and I discovered that ob_get_clean() also truncates the error_log() buffer right in the middle of its output, and well as the output buffer which it is supposed to truncate. If you are using error_log(), use ob_get_contents() and ob_end_clean() instead of ob_get_clean().