我希望这有助于:

<?php
    // The code below creates the class
    class Person {
        // Creating some properties (variables tied to an object)
        public $isAlive = true;
        public $firstname;
        public $lastname;
        public $age;

        // Assigning the values
        public function __construct($firstname, $lastname, $age) {
          $this->firstname = $firstname;
          $this->lastname = $lastname;
          $this->age = $age;
        }

        // Creating a method (function tied to an object)
        public function greet() {
          return "Hello, my name is " . $this->firstname . " " . $this->lastname . ". Nice to meet you! :-)";
        }
      }

    // Creating a new person called "boring 12345", who is 12345 years old ;-)
    $me = new Person('boring', '12345', 12345);

    // Printing out, what the greet method returns
    echo $me->greet(); 
    ?>

更多信息请访问codecademy.com

我希望这有助于:

<?php
    // The code below creates the class
    class Person {
        // Creating some properties (variables tied to an object)
        public $isAlive = true;
        public $firstname;
        public $lastname;
        public $age;

        // Assigning the values
        public function __construct($firstname, $lastname, $age) {
          $this->firstname = $firstname;
          $this->lastname = $lastname;
          $this->age = $age;
        }

        // Creating a method (function tied to an object)
        public function greet() {
          return "Hello, my name is " . $this->firstname . " " . $this->lastname . ". Nice to meet you! :-)";
        }
      }

    // Creating a new person called "boring 12345", who is 12345 years old ;-)
    $me = new Person('boring', '12345', 12345);

    // Printing out, what the greet method returns
    echo $me->greet(); 
    ?>

更多信息请访问codecademy.com

注意:如果子类定义了构造函数，父构造函数不会隐式调用。为了运行父构造函数，需要在子构造函数中调用parent::__construct()。如果子类没有定义构造函数，那么它可以像普通的类方法一样从父类继承(如果它没有声明为private)。

让我先解释一下__construct()，而不是先使用方法…关于__construct()要知道的一件事是，它是一个内置函数，好吧，让我在PHP中称它为方法。正如print_r()是用于过程的，__construct()是用于OOP的内建对象。

话虽如此，让我们来探索一下为什么应该使用这个名为__construct()的函数。

  /*=======Class without __construct()========*/
  class ThaddLawItSolution
   {
      public $description;
      public $url;
      public $ourServices;

      /*===Let us initialize a value to our property via the method set_name()==== */
     public function setName($anything,$anythingYouChoose,$anythingAgainYouChoose)
     {
      $this->description=$anything;
      $this->url=$anythingYouChoose;
      $this->ourServices=$anythingAgainYouChoose;
    }
    /*===Let us now display it on our browser peacefully without stress===*/
    public function displayOnBrowser()
    {
       echo "$this->description is a technological company in Nigeria and our domain name is actually $this->url.Please contact us today for our services:$this->ourServices";
    }
 
 }

         //Creating an object of the class ThaddLawItSolution
$project=new ThaddLawItSolution;
        //=======Assigning Values to those properties via the method created====//
$project->setName("Thaddlaw IT Solution", "https://www.thaddlaw.com", "Please view our website");
      //===========Let us now display it on the browser=======
$project->displayOnBrowser();

__construct()让你的生活非常简单，想象一下我通过该方法为这些属性赋值所花费的时间。从上面的代码中，我创建了一个对象，它是第一个，然后在最终在浏览器上显示它之前为第二个属性赋值。但是在创建对象时使用__construct()，即$project= new ThaddLawItSolution;您可以在创建对象时立即执行为该方法赋值的操作，即。

$project=new ThaddLawItSolution("Thaddlaw IT Solution", "https://www.thaddlaw.com","Please view our website");

//===现在使用__constructor=====

只需删除名为setName的方法并放入__construct();当创建一个对象时，你立即赋值。这就是整个__construct()方法背后的意义。但请注意，这是一个内置的方法或函数

__construct是一个在使用新对象之前初始化它的方法。 http://php.net/manual/en/language.oop5.decon.php#object.construct

构造函数是一个在类实例化时自动调用的方法。这意味着构造函数的内容不需要单独的方法调用就可以处理。类关键字括号的内容被传递给构造函数方法。