继承在PHP中不起作用 [英] Inheritance not working in PHP

问题描述

朋友你好。我是PHP的新手。我在PHP中尝试继承，但我无法理解一些概念。当我从子类调用print_name方法时，没有任何内容被打印出来。任何人都可以告诉我哪里出错了吗？

Hello friends. I am new to PHP. I'm trying inheritance in PHP but I'm not able to understand some concepts. When I am calling print_name method from child class nothing gets printed. Can anyone tell me where I am going wrong?

class Parent_class
{
    var $first_name="David";
    var $last_name="Hussey";
    
    function __construct()
    {
        echo "Parent class object instantiated" . "</br>";
    }
    
    function print_name($name,$surname)
    {
        $this->first_name=$name;
        $this->last_name=$surname;
        
        echo $this->first_name . " ". $this->last_name . "</br>";    
    }
}
    
class Child_class extends Parent_class
{
    var $x="Roger";
    var $y="Nadal";
    
    function __construct()
    {
        echo "Child class object instantiated" . "</br>";
    }
    
    function call_parent_class_function()
    {
        echo $this->x . " ". $this->last_name . "</br>";
        $this->print_name($x,$y);
    }
}

$obj = new Child_class;
$obj->call_parent_class_function();

$obj1 = new Parent_class;
$obj1->print_name("Virat","Kohli");

推荐答案

first_name = David;
var

first_name="David"; var

last_name = Hussey;

函数__construct（）
{
echo 实例化父类对象。 < / br>;
}

函数print_name（

last_name="Hussey"; function __construct() { echo "Parent class object instantiated" . "</br>"; } function print_name(

name，

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