PHP Manual: is

is_a

(PHP 4 >= 4.2.0, PHP 5)

is_a -- Returns TRUE if the object is of this class or has this class as one of its parents

Description

bool is_a ( object object, string class_name )

This function returns TRUE if the object is of this class or has this class as one of its parents, FALSE otherwise.

Example 1. is_a() example

<?php
// define a class
class WidgetFactory
{
  var $oink = 'moo';
}

// create a new object
$WF = new WidgetFactory();

if (is_a($WF, 'WidgetFactory')) {
  echo "yes, \$WF is still a WidgetFactory\n";
}
?>

The is_a() function is deprecated as of PHP 5 in favor of the instanceof type operator. In the above example we could use the following in PHP 5:

Example 2. Using the instanceof operator in PHP 5

<?php
if ($WF instanceof WidgetFactory) {
    echo 'Yes, $WF is a WidgetFactory';
}
?>