php 中定义类

<?php
class Car{
var $color;
function __construct($color=‘green‘){
$this->color=$color;    
}
function what_color(){
return $this->color;    
}
}
function print_var($obj){
    foreach(get_object_vars($obj) as $props=>$val){
     echo "$props=$val";    
    }
    
}
$myCar=new Car();
print_var($myCar);
//echo $myCar->what_color();
?>