PHP Magic Constants
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.
Magic Constants
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__.
