PHP Manual: Magic constants

Magic constants

There are nine magical constants that change depending on where they are used. For example, the value of __LINE__ depends on the line that it's used on in your script. All these "magical" constants are resolved at compile time, unlike regular constants, which are resolved at runtime. These special constants are case-insensitive and are as follows:

**PHP's magic constants**
Name	Description
`__LINE__`	The current line number of the file.
`__FILE__`	The full path and filename of the file with symlinks resolved. If used inside an include, the name of the included file is returned.
`__DIR__`	The directory of the file. If used inside an include, the directory of the included file is returned. This is equivalent to `dirname(__FILE__)`. This directory name does not have a trailing slash unless it is the root directory.
`__FUNCTION__`	The function name, or `{closure}` for anonymous functions.
`__CLASS__`	The class name. The class name includes the namespace it was declared in (e.g. `Foo\Bar`). When used in a trait method, __CLASS__ is the name of the class the trait is used in.
`__TRAIT__`	The trait name. The trait name includes the namespace it was declared in (e.g. `Foo\Bar`).
`__METHOD__`	The class method name.
`__NAMESPACE__`	The name of the current namespace.
`ClassName::class`	The fully qualified class name.

Magic constants

See Also