What are the global variables in php

php global variables include: 1. $_SERVER, a super-global variable of the server and execution environment information on which the current script is running; 2. $_GET, an associative array of variables passed to the current script through the GET method; 3. $_POST, an associative array of variables passed to the current script through the POST method; 4. $_SESSION, which stores user-related information in the current session; 5. $_COOKIE, an associative array of variables passed to the current script through HTTP Cookie; 6. $ _FILES and so on.

The operating system of this tutorial: Windows10 system, PHP version 8.1.3, DELL G3 computer.

PHP is a widely used open source server-side scripting language for developing dynamic websites and web applications. It provides many different variables and data types, including global variables. Global variables are variables that can be accessed from anywhere in a PHP script, even within functions. The following will introduce some common PHP global variables:

1. $_SERVER:

$_SERVER is a super variable that contains the server and execution environment information on which the current script is running. Global variables. It contains a lot of useful information, such as the name of the server, the path to the script file, the request method (GET or POST), etc.

2. $_GET:

$_GET is an associative array containing the variables passed to the current script through the GET method. The GET method is a way of passing data via a query string in the URL.

3. $_POST:

$_POST is an associative array containing the variables passed to the current script through the POST method. The POST method is a way of passing data through the body part of an HTTP request.

4. $_SESSION:

$_SESSION is a global variable that stores user-related information in the current session. It exists by maintaining session state between different pages and can be used to track the user's login status, shopping cart contents, etc.

5. $_COOKIE:

$_COOKIE is an associative array containing variables passed to the current script through HTTP Cookies. Cookies are a way of storing data on a user's computer and can be used to maintain the user's personalized settings and status between pages.

6. $_FILES:

$_FILES is a global variable that contains information about the file passed to the current script through HTTP file upload. It is an associative array that contains the name, type, size of the file, and the path of the temporary file.

In addition to the above common global variables, there are many other global variables, such as $_REQUEST (including variables passed by GET and POST methods), $_ENV (including environment variables), $_SERVER and $_ENV (contains server and environment variables), etc.

When writing PHP code, using global variables can make development more convenient and flexible. However, global variables should be used with caution, as misuse of global variables can lead to confusing and unpredictable behavior of the code. Therefore, it is recommended to use global variables reasonably when writing PHP scripts, and use local variables where possible to improve the readability and maintainability of the code.

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