PHP オブジェクト指向メモ - 123 静的プロパティと静的メソッドの図

class Human {
    static public $head = 1;    public function changeHead() {
        Human::$head = 9;
    }    public function getHead() {
        return Human::$head;
    }
}echo Human::$head; //1// 静态属性的访问方法echo &#39;<br >&#39;;// 静态属性只有一个，为所有的对象的共享.$m1 = new Human();$m1->changeHead();$m2 = new Human();$m3 = new Human();echo $m2->getHead(),&#39;<br >&#39;; //9echo $m3->getHead(),&#39;<br >&#39;; //9

class Human2 {
    public $name = '张三';    static public function cry() {
        echo '5555';
    }    public function eat() {
        echo '吃饭';
    }    public function intro() {
        echo $this->name;
    }
}// 此时一个对象都没有Human2::cry();// 下面这个eat是非静态方法，应由对象来调用Human2::eat();/*
报错提示：
Strict standards: Non-static method Human2::eat() should not be called statically
*/echo &#39;<br >&#39;;//Human2::intro();/*
直接报错：
Fatal error: Using $this when not in object context
*/

$lisi = new Human2();$lisi->cry(); //5555