Predefined variables

PHP provides a large number of predefined variables to any script. The variables represent everything from external variables to built-in environment variables, last error messages to last retrieved headers.

Superglobals

Superglobals are built-in variables that are always available in all scopes. These variables are:

$GLOBALS
$_SERVER
$_GET
$_POST
$_FILES
$_COOKIE
$_SESSION
$_REQUEST
$_ENV

Note: Superglobals cannot be used as variable variables inside functions or class methods.

$GLOBALS — References all variables available in global scope
$_SERVER — Server and execution enviroment information
$_GET — HTTP GET variables
$_POST — HTTP POST variables
$_FILES — HTTP File Upload variables
$_REQUEST — Request variables
$_SESSION — Session variables
$_ENV — Environment variables
$_COOKIE — HTTP Cookies
$php_errormsg — The previous error message
$HTTP_RAW_POST_DATA — Raw POST data
$http_response_header — HTTP response headers
$argc — The number of arguments passed to script
$argv — Array of arguments passed to script

Predefined variables

Superglobals

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