PHP 靜態(tài)關(guān)鍵字static
<?php class?glass{ public?$name; public?$height; public?$weight; public?$color; public?static?$capacity;//定義靜態(tài)變量capacity?容量 function?__construct($name,$height,$weight,$color,$capacity) //?問題1:構(gòu)造函數(shù)前面是function,不是public { $this->name=$name; $this->height=$height; $this->weight=$weight; $this->color=$color; self::$capacity=$capacity; echo?$this->name."杯子的高度為"."$height"."\n"."$this->name"."杯子的顏色為"."$color"."\n"."$this->name"."杯子的容量為"."$capacity"."\n"."\n"; } function?__destruct(){ echo?"銷毀".$this->name."杯子"."\n"; } public?static?function?ChangeCapacity($newcapacity){ self::$capacity=$newcapacity; //?echo?"$this->name"."$newcapacity"."\n"; } } $glass1=new?glass("num1","500mm","100mm","藍色","500ml"); //?$glass2=new?glass("num2","300mm","500mm","黑色","750ml"); //?$glass1->ChangeCapacity("900ml"); //問題2:修改靜態(tài)成員參數(shù)值的方法 //?應(yīng)使用? 類名::成員參數(shù)("參數(shù)值"); //輸出? echo?類名::$成員參數(shù); glass::ChangeCapacity("123"); echo?glass::$capacity."\n"; $glass3=new?glass("num3","100mm","100mm","白色","520ml"); ?>
在下面修改了glass類中capacity參數(shù)為123,但是后面再次實例化對象后,輸出的$capacity值仍為定義的"520ml",而不是修改后的值:123
2020-12-09