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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


正在回答

1 回答

http://img1.sycdn.imooc.com//5fd0899500011ebd02550039.jpg你這里這樣寫相當(dāng)于給靜態(tài)變量重新賦值,你想要的效果是構(gòu)造函數(shù)的參數(shù)值等于靜態(tài)變量的值,應(yīng)該寫成? ?$capacity?=?self::$capacity;

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