No cache version.
Caching disabled. Default setting for this page:enabled (code LNG204)If the display is too slow, you can disable the user mode to view the cached version.
Type Operators
instanceof is used to determine whether a PHP variable is an instantiated object of a certain class:
Example #1 Using instanceof with classes
<?php
class MyClass
{
}
class NotMyClass
{
}
$a = new MyClass;
var_dump($a instanceof MyClass);
var_dump($a instanceof NotMyClass);
?>
The above example will output:
bool(true) bool(false)
instanceof can also be used to determine whether a variable is an instantiated object of a class that inherits from a parent class:
Example #2 Using instanceof with inherited classes
<?php
class ParentClass
{
}
class MyClass extends ParentClass
{
}
$a = new MyClass;
var_dump($a instanceof MyClass);
var_dump($a instanceof ParentClass);
?>
The above example will output:
bool(true) bool(true)
To check if an object is not an instanceof a class, the logical not operator can be used.
Example #3 Using instanceof to check if object is not an instanceof a class
<?php
class MyClass
{
}
$a = new MyClass;
var_dump(!($a instanceof stdClass));
?>
The above example will output:
bool(true)
Lastly, instanceof can also be used to determine whether a variable is an instantiated object of a class that implements an interface:
Example #4 Using instanceof with interfaces
<?php
interface MyInterface
{
}
class MyClass implements MyInterface
{
}
$a = new MyClass;
var_dump($a instanceof MyClass);
var_dump($a instanceof MyInterface);
?>
The above example will output:
bool(true) bool(true)
Although instanceof is usually used with a literal classname, it can also be used with another object or a string variable:
Example #5 Using instanceof with other variables
<?php
interface MyInterface
{
}
class MyClass implements MyInterface
{
}
$a = new MyClass;
$b = new MyClass;
$c = 'MyClass';
$d = 'NotMyClass';
var_dump($a instanceof $b); // $b is an object of class MyClass
var_dump($a instanceof $c); // $c is a string 'MyClass'
var_dump($a instanceof $d); // $d is a string 'NotMyClass'
?>
The above example will output:
bool(true) bool(true) bool(false)
instanceof does not throw any error if the variable being tested is not
an object, it simply returns FALSE. Constants, however, are not allowed.
Example #6 Using instanceof to test other variables
<?php
$a = 1;
$b = NULL;
$c = imagecreate(5, 5);
var_dump($a instanceof stdClass); // $a is an integer
var_dump($b instanceof stdClass); // $b is NULL
var_dump($c instanceof stdClass); // $c is a resource
var_dump(FALSE instanceof stdClass);
?>
The above example will output:
bool(false) bool(false) bool(false) PHP Fatal error: instanceof expects an object instance, constant given
There are a few pitfalls to be aware of. Before PHP version 5.1.0, instanceof would call __autoload() if the class name did not exist. In addition, if the class was not loaded, a fatal error would occur. This can be worked around by using a dynamic class reference, or a string variable containing the class name:
Example #7 Avoiding classname lookups and fatal errors with instanceof in PHP 5.0
<?php
$d = 'NotMyClass';
var_dump($a instanceof $d); // no fatal error here
?>
The above example will output:
bool(false)
The instanceof operator was introduced in PHP 5. Before this time is_a() was used but is_a() has since been deprecated in favor of instanceof. Note that as of PHP 5.3.0, is_a() is no longer deprecated.
See also get_class() and is_a().
English translation
You have asked to visit this site in English. For now, only the interface is translated, but not all the content yet.If you want to help me in translations, your contribution is welcome. All you need to do is register on the site, and send me a message asking me to add you to the group of translators, which will give you the opportunity to translate the pages you want. A link at the bottom of each translated page indicates that you are the translator, and has a link to your profile.
Thank you in advance.
Document created the 30/01/2003, last modified the 26/10/2018
Source of the printed document:https://www.gaudry.be/en/php-rf-language.operators.type.html
The infobrol is a personal site whose content is my sole responsibility. The text is available under CreativeCommons license (BY-NC-SA). More info on the terms of use and the author.
References
These references and links indicate documents consulted during the writing of this page, or which may provide additional information, but the authors of these sources can not be held responsible for the content of this page.
The author This site is solely responsible for the way in which the various concepts, and the freedoms that are taken with the reference works, are presented here. Remember that you must cross multiple source information to reduce the risk of errors.
