PHP | ReflectionClass isInstance() Function

Last Updated : 12 Jul, 2025
The ReflectionClass::isInstance() function is an inbuilt function in PHP which is used to check whether the specified object is an instance of the class or not. Syntax: 
bool ReflectionClass::isInstance( object $object )
Parameters: This function accepts a single parameter object which is being searched in the instance of the class. Return Value: This function returns true for the success or false on failure. Below programs illustrate the ReflectionClass::isInstance() function in PHP: Program 1: php 
<?php

// Declaring a user-defined class
class  GFG { }

// Initialising the instance
$Instance = new GFG();

// Using ReflectionClass over the
// instance GFG
$obj = new ReflectionClass('GFG');

// Calling isInstance() function
$A = $obj->isInstance($Instance);

// Getting the value true or false
var_dump($A);
?>
Output: 
bool(true)
Program 2: php 
<?php

// Declaring a user-defined class
class  GFG { }

// Using ReflectionClass over the
// instance GFG
$obj = new ReflectionClass('GFG');

// Calling isInstance() function
$A = $obj->isInstance($obj);

// Getting the value true or false
var_dump($A);
?>
Output: 
bool(false)
Reference: https://www.php.net/manual/en/reflectionclass.isinstance.php
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