php 面向对象?

peoong

class SimpleClass{
   public $var = 'a default value';
   public function displayVar(){
      echo $this->var;
  }
}

$instance = new SimpleClass();

$obj1   =  $instance; //-----1
$obj2   =&$instance; //-----2

不知1,2 有什么区别?
(1不就是传地址,$instance 与$obj1 指向同一个实例吗? 2加了一个 & ,搞不清楚了,请大家解答下.)

bs

LZ很细心，它们没有任何区别，有区别的是对象克隆功能

liexusong

在PHP4是有区别的!在PHP5以上第二种是会产生警告的!因为PHP5对于对象的赋值就是引用的~!而PHP4就不一样!

南无小和尚

In contrast, functions that accept array and object parameters have a performance advantage when references are used. This is because arrays and objects do not use reference counting, so multiple copies of an array or object are created if "pass by value" is used. So the following code:

function ObjRef(&$o)
{
   $a =$o->name;
}

is faster than:

$function ObjRef($o)
{
  $a = $o->name;
}

Note: In PHP 5, all objects are passed by reference automatically, without the need of an explicit & in the parameter list. PHP 5 object performance should be significantly faster

参考：
http://phplens.com/lens/php-book/optimizing-debugging-php.php

pxllonga

原帖由 peoong 于 2009-6-20 13:13 发表
class SimpleClass{
   public $var = 'a default value';
   public function displayVar(){
      echo $this->var;
  }
}

$instance = new SimpleClass();

$obj1   =  $instance; //-----1
$obj ...

1是复制
2是引用内存地址

3227049

都用到public了，肯定是php5了，都是引用，类复制要用clone

qqwm

参看PHP手册“引用”部分