5 | Built-In Superglobal Variables in PHP | 2023 | Learn PHP Full Course for Beginners

Summary

In this video, the instructor introduces PHP's predefined variables, known as super globals, which are accessible globally within the code. Key super globals discussed include `$_SERVER`, `$_GET`, `$_POST`, `$_REQUEST`, `$_FILES`, `$_COOKIE`, and `$_SESSION`. Each serves a specific purpose, from retrieving server information to managing user sessions and file uploads. The instructor highlights the importance of understanding these variables for future lessons, particularly when developing practical applications, such as a calculator. Viewers are encouraged to familiarize themselves with these concepts as they progress through the course.

Takeaways

• 😀 Predefined variables, or super globals, are built-in PHP variables accessible throughout your code regardless of scope.
• 🛠️ To reference super globals, start with a dollar sign followed by an underscore and a capitalized word (e.g., $_SERVER).
• 📂 The $_SERVER super global provides server-related information, like document root and current script name.
• 🔍 The $_GET super global retrieves data sent through the URL using the GET method, allowing for dynamic data handling.
• 🔐 The $_POST super global handles form submissions via the POST method, keeping submitted data hidden from the URL for security.
• 📥 The $_FILES super global is used to manage file uploads, providing information about uploaded files' sizes and types.
• 🍪 The $_COOKIE super global accesses cookies stored on the user's computer, useful for retaining user preferences.
• 📅 The $_SESSION super global allows you to store user data across multiple pages, enabling session management on the server side.
• 🌐 The $_REQUEST super global combines data from $_GET, $_POST, and cookies, but it's best to use GET or POST for clarity.
• 🔒 The $_ENV super global deals with environment variables, which store sensitive configuration data but will be discussed in more advanced lessons.

Q & A

What are predefined variables in PHP?

Predefined variables, also known as built-in variables, are variables that exist within the PHP language, allowing access to specific information and functionalities without needing to define them.

What are superglobals in PHP?

Superglobals are a type of predefined variable in PHP that can be accessed from any scope in the code, regardless of where they are defined.

How are superglobals referenced in PHP?

Superglobals are referenced using a dollar sign followed by an underscore and a capitalized word, such as $_SERVER or $_GET.

What information can you obtain using the $_SERVER superglobal?

The $_SERVER superglobal provides information about the server environment, such as document root, server name, and request method.

What is the difference between the GET and POST methods?

The GET method sends data appended to the URL, making it visible, while the POST method sends data in the request body, keeping it hidden from the URL.

What is the purpose of the $_GET superglobal?

The $_GET superglobal is used to retrieve data sent via the URL using the GET method, allowing access to query parameters.

Why would you use the POST method over the GET method?

The POST method is preferred for submitting sensitive information, like login credentials, as it does not expose data in the URL.

What is the $_FILES superglobal used for?

The $_FILES superglobal is used to gather information about files uploaded through an HTML form, including file size, name, and type.

How does the $_SESSION superglobal work?

The $_SESSION superglobal is used to store user-specific data on the server that persists across multiple pages during a user's session.

What are environment variables in PHP?

Environment variables store sensitive data related to the server environment and are accessed via the $_ENV superglobal, though they are not discussed in detail for beginners.