is_subclass

描述

bool is_subclass_of ( object object, string class_name )

如果对象 object 所属类是类 class_name 的子类，则返回 TRUE，否则返回 FALSE。

参见 get_class()、 get_parent_class() 和 is_a()。

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Ondra Zizka
13-Oct-2006 08:31


For PHP4:



/** Returns whether specified class is subclass of the other class. */

function is_subclass($sClass, $sExpectedParentClass){

    do if( $sExpectedParentClass === $sClass ) return true;

    while( false != ($sClass = get_parent_class($sClass)) );

    return false;

}

// Test:

class A {} class B extends A {} class C extends B {} echo (int) is_subclass('C', 'A');

gunniboyh at web dot de
20-May-2006 09:16


is_subclass_of() works also with classes between the class of obj and the superclass.



example:

<?php

class A {};

class B extends A {};

class C extends B {};



$foo=new C();

echo ((is_subclass_of($foo,'A')) ? 'true' : 'false');

?>



echoes 'true' .

01-Oct-2005 09:32


this function does not check interfaces, unlike instanceof operator.

youcantryreachingme at REMOVEME dot hotmail dot com
22-Mar-2005 10:15


A bug report at http://pear.php.net/bugs/bug.php?id=2975 indicates that the "is_subclass_of" function can return the error message:



Warning: Unknown class passed as parameter



in the event that the class represented by the second argument hasn't yet been instantiated.

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