array ( 0 => 'index.php', 1 => 'PHP Manual', ), 'head' => array ( 0 => 'UTF-8', 1 => 'en', ), 'this' => array ( 0 => 'function.flush.php', 1 => 'flush', 2 => 'Flush system output buffer', ), 'up' => array ( 0 => 'ref.outcontrol.php', 1 => 'Output Control Functions', ), 'prev' => array ( 0 => 'ref.outcontrol.php', 1 => 'Output Control Functions', ), 'next' => array ( 0 => 'function.ob-clean.php', 1 => 'ob_clean', ), 'alternatives' => array ( ), 'source' => array ( 'lang' => 'en', 'path' => 'reference/outcontrol/functions/flush.xml', ), 'history' => array ( ), ); $setup["toc"] = $TOC; $setup["toc_deprecated"] = $TOC_DEPRECATED; $setup["parents"] = $PARENTS; manual_setup($setup); contributors($setup); ?>

flush

(PHP 4, PHP 5, PHP 7, PHP 8)

flush — Flush system output buffer

Description

flush(): void

Flushes the system write buffers of PHP and the backend used by PHP (e.g.: CGI, a web server). In a command line environment flush() will attempt to flush the contents of the buffers only whereas in a web context headers and the contents of the buffers are flushed.

Note: flush() may not be able to override the buffering scheme of the web server and it has no effect on any client-side buffering in the browser.

Note: This function does not have any effect on user level output handlers such as those started by ob_start() or output_add_rewrite_var().

Warning

flush() can interfere with output handlers that set and send headers in a web context (e.g. ob_gzhandler()) by sending headers before these handlers can do so.

Parameters

This function has no parameters.

Return Values

No value is returned.

Changelog

Version Description
8.4.0 Flushing headers without a body will now succeed in FastCGI.

See Also