PHP has large number of predefined constants. This HOWTO will present the seven most important, most practical and most useful PHP Magic Constants.

  • __FILE__ – The full path and filename of the file.
  • __DIR__ – The directory of the file.
  • __FUNCTION__ – The function name.
  • __CLASS__ – The class name.
  • __METHOD__ – The class method name.
  • __LINE__ – The current line number of the file.
  • __NAMESPACE__ – The name of the current namespace

This is example PHP script with comments, which demonstrate howto use all previously mentioned PHP Magic Constants.

<?php // Set namespace (works only with PHP 5.3) namespace TestProject; // This prints file full path and name echo "This file full path and file name is '" . __FILE__ . "'.\n"; // This prints file full path, without file name echo "This file full path is '" . __DIR__ . "'.\n"; // This prints current line number on file echo "This is line number " . __LINE__ . ".\n"; // Really simple basic test function function test_function_magic_constant() { echo "This is from '" . __FUNCTION__ . "' function.\n"; } // Prints function and used namespace test_function_magic_constant(); // Really simple class for testing magic constants class TestMagicConstants { // Prints class name public function printClassName() { echo "This is " . __CLASS__ . " class.\n"; } // Prints class and method name public function printMethodName() { echo "This is " . __METHOD__ . " method.\n"; } // Prints function name public function printFunction() { echo "This is function '" . __FUNCTION__ . "' inside class.\n"; } // Prints namespace name (works only with PHP 5.3) public function printNamespace() { echo "Namespace name is '" . __NAMESPACE__ . "'.\n"; } } // Create new TestMagicConstants class $test_magic_constants = new TestMagicConstants; // This prints class name and used namespace $test_magic_constants->printClassName(); // This prints method name and used namespace $test_magic_constants->printMethodName(); // This prints function name inside class and used namespace // same as method name, but without class $test_magic_constants->printFunction(); // This prints namespace name (works only with PHP 5.3) $test_magic_constants->printNamespace(); ?>


This file full path and file name is '/tmp/magic_constants/magic.php'.
This file full path is '/tmp/magic_constants'.
This is line number 13.
This is from 'TestProject\test_function_magic_constant' function.
This is TestProject\TestMagicConstants class.
This is TestProject\TestMagicConstants::printMethodName method.
This is function 'printFunction' inside class.
Namespace name is 'TestProject'.

Posted by Web Monkey