example:<?php class Example{ static $num=0; function __construct(){ } } class Children extends Example{ function __construct(){ self::$num+=1; } } class Childrentwo extends Example{ function ob(){ echo self::$num; } } $obj2=new Childrentwo(); echo 'result1:'.$obj2->ob(); //output: result1:0 $obj=new Children(); //echo $obj->$num,'<br/>';实例化->读取静态变量无效 echo "result2:".$obj::$num.'<br/>'; //output: result2:1 echo "result3:".Example::$num.'<br/>'; //output: result3:1 ?>
