1 
     '; 4  5 $obj = new StdClass; 6 $obj->name = 'Pig'; 7 var_dump($obj);                    　//object(stdClass)#1 (1) { ["name"]=> string(3) "Pig" } 8                  9 $copy = $obj;                    　　// $obj ,$copy都是new StdClass返回的同一个标识符的拷贝10 var_dump($copy);                　　 //object(stdClass)#1 (1) { ["name"]=>string(3) "Pig" }11                 12 $objRef = &$obj;                　　 // 此时会将$obj转换成引用，然后赋值给$objRef，因此$obj,$objRef都为引用                13 var_dump($objRef);                  //object(stdClass)#1 (1) { ["name"]=>string(3) "Pig" }14 15 $objClone = clone $obj;             //新空间16 $obj->name = 'After Clone';17 var_dump($objClone);            　　//object(stdClass)#1 (1) { ["name"]=>string(3) "Pig" }18 var_dump($obj);                    //object(stdClass)#1 (1) { ["name"]=>string(11) "After Clone" }19 20 //unset是删除引用效果21 $nameRef = &$obj->name;            //$obj->name被转换成引用（& string），然后赋给$nameRef22 var_dump($obj);                    //object(stdClass)#2 (1) { ["name"]=>&string(11) "After Clone" }23 unset($nameRef);                　 //删除引用24 var_dump($obj);                    //object(stdClass)#1 (1) { ["name"]=>string(11) "After Clone" }25         26 //null是赋值效果        27 $nameRef = &$obj->name;            //恢复name的引用28 var_dump($obj);                    //object(stdClass)#2 (1) { ["name"]=>&string(11) "After Clone" }29 $nameRef = null;                30 var_dump($obj);                    //object(stdClass)#2 (1) { ["name"]=>&NULL }31 32 unset($objRef);                    //仅仅删除了引用33 var_dump($obj);                    //object(stdClass)#1 (1) { ["name"]=>&NULL }34 35 $objRef = &$obj;                　 //恢复对象引用36 $obj->name = 'Lucy';37 $obj = null;                   　　//赋值$obj为null，$obj只是new StdClass的标识拷贝，不会影响其内容。38                                   //$objRef做为$obj的引用，会同时被赋值null39                                   //等价 $objRef = null;40 41 var_dump($obj,$copy,$objRef,$objClone);42 // NULL,43 // object(stdClass)#1 (1) { ["name"]=>&string(4) "Lucy" },44 // NULL,45 // object(stdClass)#1 (1) { ["name"]=>string(3) "Pig" }46 47 ?>