PHP: INSTANCEOF

[edit] Last updated: Fri, 25 May 2012

INSTANCEOF

PHP code


<?php
/*
 * 
 * opcode number: 138
 */
$obj = new A();

if ($obj instanceof A) {
   echo 'A';
}
?>

PHP opcodes

Function name: (null)

Compiled variables: !0=$obj

line	#	op	ext	return	operands
6	0	ZEND_FETCH_CLASS		:0	'A'
	1	NEW		$1	:0
	2	DO_FCALL_BY_NAME	0
	3	ASSIGN			!0,$1
8	4	ZEND_FETCH_CLASS		:4	'A'
	5	ZEND_INSTANCEOF		~5	!0,$4
	6	JMPZ			~5,->9
9	7	ECHO			'A'
10	8	JMP			->9
11	9	RETURN			1

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asdf at asdf dot com 03-Apr-2012 10:13


Please note, that you get no warnings on non-existent classes:



<?php

class A() {

}



$a = new A();



$exists = ($a instanceof A); //TRUE

$exists = ($a instanceof NonExistentClass); //FALSE

Sasanapuri Satish 13-Jul-2011 01:46


The operator instanceof can also be used to determine whether an object of a class is inheriting property from another class or not. 



Example:



<?php



class test

{    var $var;

    function disp()

   {

       echo "Inside the class";

   }

}



$obj=new test;



var_dump($obj instanceof test); // Prints bool(true) 



?>

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