what exactly is $_REQUEST[$K] in PHP?

$_REQUEST[$k] = isset($_GET[$k]) ? $_GET[$k] : $_POST[$k];

or开发者_JAVA技巧

$_REQUEST[$k] = isset($_POST[$k]) ? $_POST[$k] : $_GET[$k];

Which is the case,reason?

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$_REQUEST is the union of $_GET, $_POST, and $_COOKIE where variables_order and since PHP 5.3 request_order defines the order.

The default order is GET, POST, and then cookie. That means POST parameters overwrite existing GET parameters and cookies overwrite existing POST and GET parameters.

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ini directive "variables_order" is believed* to affect $_REQUEST, see http://php.net/manual/en/ini.core.php

*"believed" because i never used either that or $_REQUEST itself.

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$_REQUEST is simply the array that PHP puts all of the GET and POST and COOKIE parameters into, with precedence in that order in the case of conflicts.

http://php.net/manual/en/reserved.variables.request.php