OOP PHP 起始级别 - 它没有得到名称。不显示任何东西

Question

我刚开始（现在）尝试学习 OOP PHP，我不敢相信我已经卡住了！

我找不到很多容易理解的教程（我有一个来自 killerphp 的初学者教程，但我想我可能需要较低的级别...），问题是...

教程告诉我创建 2 个文件； index.php 和 class_lib.php:

class_lib.php

<?php
class Person { //we define a class adding class before the name of the class
    //Properties of the person class
    var $name;
 }

index.php

<!DOCTYPE html>
<html>
<head>
 <title>Learning OOP PHP</title>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0"> 
<?php include ("class_lib.php"); ?>
</head>
<body>
<?php
     $stefan = new Person();
     $stefan->set_name("Stefan Grey");     
     echo "Stefan's full name is: " . $stefan->get_name();
?>
</body>
</html>

有谁能解释一下为什么它不输出 "Stefan's full name is: Stefan Grey" 吗？事实上它没有显示任何东西：/

如果有人知道面向真正傻瓜的 OOP 教程（我需要基本的解释和简单的，我的理解力很差，我总是需要阅读一千遍才能理解它们的意思）。

谢谢！！

Answer 1

作为@先生。前面提到外星人，你的class里没有getter和setter方法。

class_lib.php

<?php
class Person { //we define a class adding class before the name of the class
    //Properties of the person class
   var $name;
    function set_name($new_name) 
    {
        $this->gt_name = $new_name;
    } 
    function get_name() 
    {
            return $this->gt_name;
    } 
 }
 ?>

index.php

<!DOCTYPE html>
<html>
<head>
 <title>Learning OOP PHP</title>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0"> 
<?php include ("class_lib.php"); ?>
</head>
<body>
<?php
     $stefan = new Person();
     $stefan->set_name("Stefan Grey");     
     echo "Stefan's full name is: " . $stefan->get_name();
?>
</body>
</html>

Answer 2

<?php
     //initializing your class
 $stefan = new Person();

     //accessing "public function set_name($name)" in class
 $stefan->set_name("Stefan Grey");

     //accessing "public function get_name()" in class
 echo "Stefan's full name is: " . $stefan->get_name();
?>

您正在访问未在 class 中定义的函数 - 也许您应该尝试在 class 中添加这些函数 - 可能像这样：

<?php
 class Person {
     //we define a class adding class before the name of the class
     //Properties of the person class
     private $name = "";

     //this is a "setter-function", for setting values, that are not accessible from outside - so you have control over what is set
     public function set_name ($name)
     {
         if ($name != "Captain Jack Sparrow") {
             $this->name = $name;
         }
     }

     //this is a "getter-function", for getting values from non-public vars - you can also do manipulation here
     public function get_name ()
     {
         if ($this->name != "") { //if $this->name is not "" (Empty String),
             return $this->name; //return $this->name to your ->get_name() position
         } else { //else (if $this->name is "" (Empty String)
             return "Nemo"; //return a standard-value
         }
     }
 }

这就是 "encapsulation" 您正在寻找的 oop-class 概念。

php 有很多语言的很棒的文档 - 可能你会在这里闲逛一段时间： http://php.net/manual/en/language.oop5.php

OOP PHP 起始级别 - 它没有得到名称。不显示任何东西

OOP PHP start level - It does not get the name. Does not display anything

php

oop

class-library

class_lib.php

index.php