What are the predefined variables in php

Predefined variables in php include $GLOBALS, $_SERVER, $_GET, $_POST, $_FILES, $_COOKIE, $_SESSION, $_REQUEST, $_ENV, $argc and $argv, etc. Detailed description: 1. $GLOBALS, contains all variables in the global scope; 2. $_SERVER, can be used to obtain the file name of the current script, etc.; 3. $_GET, an array of variables passed to the current script through the URL, etc. wait.

The operating environment of this article: Windows 10 system, PHP8.1.3 version, Dell G3 computer.

In PHP, there are many predefined variables, which are called superglobal variables. These variables are available in all scopes, including functions, class methods, and the global scope.

The following are some common predefined variables in PHP:

$GLOBALS: This variable is an associative array that contains all variables in the global scope. Global variables can be accessed through $GLOBALS[‘variable_name’].

$_SERVER: Variable containing server environment information. It can be used to obtain the file name of the current script, the IP address of the server, the request method, etc. Common $_SERVER variables include:

• $_SERVER[‘PHP_SELF’]: The file name of the currently executing script.

• $_SERVER[‘SERVER_NAME’]: The host name of the server where the script is currently running.

• $_SERVER[‘REQUEST_METHOD’]: The method used by the current request, such as GET, POST, etc.

#$_GET: An array containing the variables passed to the current script through the URL. URL parameters can be accessed through $_GET[‘variable_name’].

$_POST: An array containing the variables passed to the current script via the HTTP POST method. POST parameters can be accessed through $_POST[‘variable_name’].

$_FILES: An array containing variables for files uploaded through the HTTP POST method. Uploaded file information can be accessed through $_FILES[‘file_name’].

$_COOKIE: An array containing variables passed to the current script via HTTP cookies. The value of the cookie can be accessed through $_COOKIE[‘variable_name’].

$_SESSION: An array containing variables in the current session. Session variables can be accessed through $_SESSION[‘variable_name’].

$_REQUEST: An array containing the variables passed to the current script through HTTP requests (GET, POST and COOKIE). Request parameters can be accessed through $_REQUEST[‘variable_name’].

$_ENV: An array containing environment variables set by the operating system or web server. Environment variables can be accessed through $_ENV[‘variable_name’].

In addition to the above super global variables, there are some other predefined variables, such as:

$argc: Contains the number of command line parameters.

$argv: Array containing command line parameters.

These variables are predefined in PHP and can be used directly. By using these predefined variables, we can easily obtain some commonly used information, which facilitates our processing and judgment during development.

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