All 7 Constants & Superglobals questions
More in Constants & Superglobals
What is a constant in PHP, and how does it differ from a regular variable? How do you safely retrieve values from superglobals like $_GET or $_POST to avoid undefined index errors and potential security issues? What is the difference between class constants and global constants, and how do you define and access a constant within a class? How does the $_SERVER superglobal provide useful information about the current request and server environment? How do enums, introduced in PHP 8.1, provide a more type safe alternative to using class constants for representing a fixed set of related values? What security risks are associated with directly trusting values from superglobals like $_SERVER, and how should applications guard against header spoofing?
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PHP › Constants & Superglobals

What are PHP superglobals, and what are some of the most commonly used ones?

Beginner

Answer

Superglobals are built in PHP variables that are always accessible from any scope throughout a script, including inside functions and classes, without needing to explicitly declare them as global, and commonly used superglobals include $_GET and $_POST for accessing submitted form or URL data, $_SESSION for accessing session data, $_SERVER for accessing information about the current request and server environment, and $_FILES for accessing uploaded file information.
echo $_SERVER['REQUEST_METHOD'];
$username = $_POST['username'] ?? '';
Real-world example A login form reads the submitted username and password directly from the $_POST superglobal after the form is submitted, without needing to pass that data through any additional function parameters.

Common follow-ups: Why are superglobals accessible everywhere without needing to be declared global first?;What security precautions should be taken when using data from superglobals like $_GET or $_POST?

Security;Form Handling & Validation
All 7 Constants & Superglobals questions