php魔法函数与变量
php魔法函数与变量
1:php魔法函数
__construct()
实例化对象时被调用。
当__construct和以类名为函数名的函数同时存在时,__construct将被调用,另一个不被调用。
__destruct()
当删除一个对象或对象操作终止时被调用。
__call() 对象调用某个方法,
若方法存在,则直接调用;若不存在,则会去调用__call函数。
__get() 读取一个对象的属性时.
若属性存在,则直接返回属性值;若不存在,则会调用__get函数。
__set() 设置一个对象的属性时.
若属性存在,则直接赋值;若不存在,则会调用__set函数。
__toString()
打印一个对象的时被调用。如echo $obj;或print $obj;
__clone()
克隆对象时被调用。如:$t=new Test();$t1=clone $t;
__sleep()
serialize之前被调用。若对象比较大,想删减一点东东再序列化,可考虑一下此函数。
__wakeup()
unserialize时被调用,做些对象的初始化工作。
__isset()
检测一个对象的属性是否存在时被调用。如:isset($c->name)。
__unset()
unset一个对象的属性时被调用。如:unset($c->name)。
__set_state()
调用var_export时,被调用。用__set_state的返回值做为var_export的返回值。
__autoload()
实例化一个对象时,如果对应的类不存在,则该方法被调用。
2:魔法变量
__LINE__
返回文件中的当前行号。
__FILE__
返回文件的完整路径和文件名。如果用在包含文件中,则返回包含文件名。自PHP 4.0.2 起,__FILE__ 总是包含一个绝对路径,而在此之前的版本有时会包含一个相对路径。
__FUNCTION__
返回函数名称(PHP4.3.0新加)。自PHP5起本常量返回该函数被定义时的名字(区分大小写)。在PHP4中该值总是小写字母的。
__CLASS__
返回类的名称(PHP4.3.0 新加)。自PHP5起本常量返回该类被定义时的名字(区分大小写)。在PHP4中该值总是小写字母的。
__METHOD__
返回类的方法名(PHP5.0.0新加)。返回该方法被定义时的名字(区分大小写)。

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