what is magic constant in php code example

Example: magic constant in php

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.
__CLASS__	    The class name. The class name includes the namespace 
                it was declared in (e.g. Foo\Bar). 
__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.