How to call static attributes and static methods in php

Static properties and methods (including static and non-static) have only one location in memory (instead of static properties, there are as many properties as there are instantiated objects).

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Example:

header("content-type:text/html;charset=utf-8");

class Human{

static public $name = "小妹";

public $height = 180;

static public function tell(){

echo self::$name;//静态方法调用静态属性，使用self关键词

//echo $this->height;//错。静态方法不能调用非静态属性

//因为 $this代表实例化对象，而这里是类，不知道 $this 代表哪个对象

}

public function say(){

echo self::$name . "我说话了";

//普通方法调用静态属性，同样使用self关键词

echo $this->height;

}

}

$p1 = new Human();

$p1->say();

$p1->tell();//对象可以访问静态方法

echo $p1::$name;//对象访问静态属性。不能这么访问$p1->name

//因为静态属性的内存位置不在对象里

Human::say();//错。say()方法有$this时出错；没有$this时能出结果

//但php5.4以上会提示

?>

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Summary:

(1) Static properties can be called without instantiation. Because the static attributes are stored in the class, the calling method is "class name::property name";

(2) Static methods can be called without instantiation. Same as above

(3) Static methods cannot call non-static properties. Because non-static properties need to be instantiated and stored in the object;

(4) Static methods can call non-static methods using the self keyword. In PHP, after a method is called self::, it is automatically converted into a static method;

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