解析PHP5析构函数的具体使用方法_PHP教程-php教程-PHP中文网

解析PHP5析构函数的具体使用方法_PHP教程

php中文网

发布： 2016-07-15 13:29:11

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在升级版的在php5中，则使用__construct()来命名构造函数，而不再是与类同名，这样做的好处是可以使构造函数独立于类名，当类名改变时，不需要在相应的去修改构造函数的名称。

与构造函数相反，在PHP5中，可以定义一个名为__destruct()的函数，称之为PHP5析构函数，PHP将在对象在内存中被销毁前调用析构函数，使对象在彻底消失之前完成一些工作。对象在销毁一般可以通过赋值为null实现。

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<OL class=dp-xml><LI class=alt><SPAN><STRONG><FONT color=#006699><SPAN class=tag><?</SPAN><SPAN class=tag-name>php</SPAN></FONT></STRONG><SPAN> </SPAN></SPAN><LI class=""><SPAN>/*  </SPAN><LI class=alt><SPAN> * Created on 2009-11-18  </SPAN><LI class=""><SPAN> *  </SPAN><LI class=alt><SPAN> * To change the template for this generated file go to  </SPAN><LI class=""><SPAN> * Window - Preferences - PHPeclipse - PHP - Code Templates  </SPAN><LI class=alt><SPAN> */  </SPAN><LI class=""><SPAN> class student{  </SPAN><LI class=alt><SPAN>  //属性  </SPAN><LI class=""><SPAN>  private $no;  </SPAN><LI class=alt><SPAN>  private $name;  </SPAN><LI class=""><SPAN>  private $gender;  </SPAN><LI class=alt><SPAN>  private $age;  </SPAN><LI class=""><SPAN>    </SPAN><LI class=alt><SPAN>  private static $</SPAN><SPAN class=attribute><FONT color=#ff0000>count</FONT></SPAN><SPAN>=</SPAN><SPAN class=attribute-value><FONT color=#0000ff>0</FONT></SPAN><SPAN>;  </SPAN></SPAN><LI class=""><SPAN>  function __construct($pname)  </SPAN><LI class=alt><SPAN>  {  </SPAN><LI class=""><SPAN>   $this-</SPAN><SPAN class=tag><STRONG><FONT color=#006699>></FONT></STRONG></SPAN><SPAN class=attribute><FONT color=#ff0000>name</FONT></SPAN><SPAN> = $pname;  </SPAN></SPAN><LI class=alt><SPAN>   self::$count++;  </SPAN><LI class=""><SPAN>  }  </SPAN><LI class=alt><SPAN>    </SPAN><LI class=""><SPAN>  function __destruct()  </SPAN><LI class=alt><SPAN>  {  </SPAN><LI class=""><SPAN>   self::$count--;  </SPAN><LI class=alt><SPAN>  }  </SPAN><LI class=""><SPAN>    </SPAN><LI class=alt><SPAN>  static function get_count()  </SPAN><LI class=""><SPAN>  {  </SPAN><LI class=alt><SPAN>   return self::$count;  </SPAN><LI class=""><SPAN>  }  </SPAN><LI class=alt><SPAN> }  </SPAN><LI class=""><SPAN>   </SPAN><LI class=alt><SPAN> $</SPAN><SPAN class=attribute><FONT color=#ff0000>s1</FONT></SPAN><SPAN>=</SPAN><SPAN class=attribute-value><FONT color=#0000ff>new</FONT></SPAN><SPAN> student("Tom");  </SPAN></SPAN><LI class=""><SPAN> print(student::get_count());  </SPAN><LI class=alt><SPAN>   </SPAN><LI class=""><SPAN> $</SPAN><SPAN class=attribute><FONT color=#ff0000>s2</FONT></SPAN><SPAN>=</SPAN><SPAN class=attribute-value><FONT color=#0000ff>new</FONT></SPAN><SPAN> student("jerry");  </SPAN></SPAN><LI class=alt><SPAN> print(student::get_count());  </SPAN><LI class=""><SPAN>   </SPAN><LI class=alt><SPAN> $</SPAN><SPAN class=attribute><FONT color=#ff0000>s1</FONT></SPAN><SPAN>=</SPAN><SPAN class=attribute-value><FONT color=#0000ff>NULL</FONT></SPAN><SPAN>;  </SPAN></SPAN><LI class=""><SPAN> print(student::get_count());  </SPAN><LI class=alt><SPAN>   </SPAN><LI class=""><SPAN> $</SPAN><SPAN class=attribute><FONT color=#ff0000>s2</FONT></SPAN><SPAN>=</SPAN><SPAN class=attribute-value><FONT color=#0000ff>NULL</FONT></SPAN><SPAN>;  </SPAN></SPAN><LI class=alt><SPAN> print(student::get_count());  </SPAN><LI class=""><SPAN></SPAN><SPAN class=tag><STRONG><FONT color=#006699>?></FONT></STRONG></SPAN><SPAN> </SPAN></SPAN></LI></OL>

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上面这段代码就是PHP5析构函数的具体使用方法，希望对大家有所帮助。