PHP Magic Constant

There are a number of predefined constants available to your scripts.
We will use these constants as we need them; there’s a sample:

PHP: Magic Constant

PHP Magic Constant
__LINE__	The current line number of the file.
__FILE__	The full path and filename of the file.
__FUNCTION__	The function name
__CLASS__	The class name
__METHOD__	The class method name
PHP_VERSION	The PHP version
PHP_INT_MAX	The PHP integer value limit

---

__LINE__

eg

<?php
   echo "The Line number : ". __LINE__;
?>

 Output : The Line number : 2

---

__FILE__

eg

<?php
echo  "Your file name :". __FILE__;

?>

 Output : Your file name : C:\xampplite\htdocs\magic_constant\file.php

---

__FUNCTION__

__CLASS__

__METHOD__

eg

<?php
class demo
{
      function test()
      {
            echo "Function of demo class : ". __FUNCTION__ ."<br/>";
      }
      function testme()
      {
                echo "Method of demo class : ". __METHOD__ ."<br/>";
    echo "Class : ". __CLASS__;
    
      }
}
$object=new demo();
$object->test();
$object->testme();
?>

 Output:
Function of demo class : test
Method of demo class : demo::testme
Class : demo

---

PHP_VERSION

eg

<?php
  echo "Current PHP Version you are using  : ".PHP_VERSION;
?>

 Output : Current PHP Version you are using : 5.3.1

---

PHP_INT_MAX

eg

<?php
  echo "Integer Maximum Value : ".PHP_INT_MAX;
?>

 Output : Integer Maximum Value : 2147483647