<p>http://www.cnblogs.com/longzhongren/p/5852182.html</p><p></p><p>如果对象 object所属类是类 class_name的子类，则返回 TRUE ，否则返回 FALSE 。</p><p>例子：</p><br /><p>// define a class<br /> class  WidgetFactory<br /> {<br />  var  $oink  =  'moo' ;<br />}<br /> <br />// define a child class<br /> class  WidgetFactory_Child  extends  WidgetFactory<br /> {<br />  var  $oink  =  'oink' ;<br />}<br /> <br />// create a new object<br /> $WF  = new  WidgetFactory ();<br /> $WFC  = new  WidgetFactory_Child ();<br /> <br />if ( is_subclass_of ( $WFC ,  'WidgetFactory' )) {<br />  echo  "yes,  WFC  is a subclass of WidgetFactoryn" ;<br />} else {<br />  echo  "no,  WFC  is not a subclass of WidgetFactoryn" ;<br />}<br /> <br /><br />if ( is_subclass_of ( $WF ,  'WidgetFactory' )) {<br />  echo  "yes,  WF  is a subclass of WidgetFactoryn" ;<br />} else {<br />  echo  "no,  WF  is not a subclass of WidgetFactoryn" ;<br />}<br /> <br /><br />// usable only since PHP 5.0.3<br /> if ( is_subclass_of ( 'WidgetFactory_Child' ,  'WidgetFactory' )) {<br />  echo  "yes, WidgetFactory_Child is a subclass of WidgetFactoryn" ;<br />} else {<br />  echo  "no, WidgetFactory_Child is not a subclass of WidgetFactoryn" ;<br />}</p><p><br /></p><p><br /></p><p></p><p>运行结果：</p>yes, WFC is a subclass of WidgetFactory no, WF is not a subclass of WidgetFactory yes, WidgetFactory_Child is a subclass of WidgetFactory<br />