PHP Magic Constants

Posted 2024-05-17 07:40:16

PHP Predefined Constants

PHP has nine predefined constants that change value depending on where they are used, and therefor they are called "magic constants".

These magic constants are written with a double underscore at the start and the end, except for the ClassName::class constant.

Here are the magic constants, with descriptions and examples:

Constant	Description
__CLASS__	If used inside a class, the class name is returned.	Try it »
__DIR__	The directory of the file.	Try it »
__FILE__	The file name including the full path.	Try it »
__FUNCTION__	If inside a function, the function name is returned.	Try it »
__LINE__	The current line number.	Try it »
__METHOD__	If used inside a function that belongs to a class, both class and function name is returned.	Try it »
__NAMESPACE__	If used inside a namespace, the name of the namespace is returned.	Try it »
__TRAIT__	If used inside a trait, the trait name is returned.	Try it »
ClassName::class	Returns the name of the specified class and the name of the namespace, if any.	Try it »

Note:

The magic constants are case-insensitive, meaning __LINE__ returns the same as __line__.

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