Using the get_parent_class function
The get_parent_class() function will return the parent class name for the specified subclass.
demo.php
<?php
include_once("class1.php");
$myObj = new subclass1();
echo "Parent class: ".get_parent_class($myObj);
?>
class1.php
<?php
class class1 {
}
class subclass1 extends class1 {
}
?>