PHP-property_exists()函数

<?php
    header(‘content-type:text/html;charset=utf-8‘);
    //property_exists说明

    class A{
        public $name;
        protected $food;

        public function __construct($name, $food){
            $this->name = $name;
            $this->food = $food;
        }
    }

    $a = new A(‘小猫‘, ‘鱼儿‘);
    
    unset($a->name);

    echo‘<pre>‘;
    var_dump($a);

    if(property_exists($a, ‘name‘)){
        echo ‘<br> name属性存在‘;
    }

    //属性的重载
    $a->age = 100;

    echo ‘<pre>‘;
    var_dump($a);

    if(property_exists($a, ‘age‘)){
        echo ‘<br> age属性存在‘;
    }else{
        echo ‘<br> age属性不存在‘;
    }

    unset($a->age);
    echo ‘<pre>‘;
    echo ‘<br>---------<br>‘;
    var_dump($a);

    if(property_exists($a, ‘age‘)){
        echo ‘<br> age属性存在‘;
    }else{
        echo ‘<br> age属性不存在‘;
    }