php man page for class_exists

CLASS_EXISTS(3) 							 1							   CLASS_EXISTS(3)

class_exists - Checks if the class has been defined

SYNOPSIS
       bool class_exists (string  $class_name, [bool  $autoload = true])

DESCRIPTION
	This function checks whether or not the given class has been defined.

PARAMETERS
	      o $class_name
		- The class name. The name is matched in a case-insensitive manner.

	      o $autoload
		- Whether or not to call __autoload by default.

RETURN VALUES
	Returns TRUE if $class_name is a defined class, FALSE otherwise.

CHANGELOG
       +--------+---------------------------------------------------+
       |Version |						    |
       |	|						    |
       |	|		     Description		    |
       |	|						    |
       +--------+---------------------------------------------------+
       | 5.0.2	|						    |
       |	|						    |
       |	|  No  longer  returns TRUE for defined interfaces. |
       |	| Use interface_exists(3).			    |
       |	|						    |
       +--------+---------------------------------------------------+
EXAMPLES
       Example #1

	      class_exists(3) example

	      <?php
	      // Check that the class exists before trying to use it
	      if (class_exists('MyClass')) {
		  $myclass = new MyClass();
	      }

	      ?>

       Example #2

	      $autoload parameter example

	      <?php
	      function __autoload($class)
	      {
		  include($class . '.php');

		  // Check to see whether the include declared the class
		  if (!class_exists($class, false)) {
		      trigger_error("Unable to load class: $class", E_USER_WARNING);
		  }
	      }

	      if (class_exists('MyClass')) {
		  $myclass = new MyClass();
	      }

	      ?>

SEE ALSO
       function_exists(3), interface_exists(3), get_declared_classes(3).

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