PHP Magic Constants are same as PHP Constants. The word Magic is attached only cause of unique feature of PHP Magic Constants to change their values on the basis of their use.
PHP Magic Constants are case insensitive and they starts and ends with a double underscore (__).
|__LINE__||Used to represent current line number where it is used.|
|__FILE__||Used to represent full path and name of the file.|
|__CLASS__||Used to represent the function name where it is used.|
|__METHOD__||Used to represent the name of the class method where it is used.|
|__DIR__||Used to represent full directory path of the file.|
|__NAMESPACE__||Used to represent the name of the current namespace.|
|__FUNCTION__||Used to represents the function name where it is used.|
|__TRAIT__||Used to represent the trait name where it is used.|
<!DOCTYPE html> <html> <body> <?php echo “<p>Example for __LINE__</p>”; echo __LINE__ . "<br><br>"; echo “<p>Example for __FILE__</p>”; echo __FILE__ . "<br><br>"; echo “<p>Example for __DIR__</p>”; echo __DIR__ . "<br><br>"; ?> </body> </html>