PHP parent

php parent In object-oriented grammar, it represents “ Parent class ”, In essence, it represents the parent class “ class ”, Not the parent “ object ”, Its usage is “parent:: Properties or methods ;”.

keyword	meaning	Use location	Examples of use
parent：	Represents the parent class （ This class ）	It must be in one way	parent：： Properties or methods ;
self：	Represents the current class	It must be in one way	self：： Static property or method
$this：	Represents the object that calls the current method	It must be in one way	$this-> Instance property or method ;

<?php
  class Person{
      protected $name;
      protected $sex;
      protected $age;

    function __construct($name="", $sex=" male ", $age=1){
        $this->name = $name;
        $this->sex = $sex;
        $this->age = $age;
    }

    function say(){
        echo " My name ： ".$this->name.",  Gender ： ".$this->sex,",  Age ： ".$this->age;
    }
  }  
  
  class Student extends Person{
      private $school; // Add a school in the student class school Member properties of .

      // Override constructor in parent class , Add a school attribute to the parameter list , Used to create objects and initialize member properties 
      function __construct($name="", $sex=" male ", $age=1, $school=""){
        parent::__construct($name, $sex, $age);
        $this->school = $school;
      }

      function stydy(){
          echo $this-name." is ".$this->school." Study ";
      }
    
      function say(){
        parent::say();  // Call the method in the parent class that is overridden by this method 
        echo " stay ".$this->school." School ";
      }
  }

  $student = new Student(" Zhang San ", " Woman ", "23", "edu");// Create a student object , And pass it to a school name parameter 
  $student->say();// Call the speaking method in the student class that overrides the parent class 
  /** The result is ：  My name ：  Zhang San ,  Gender ：  Woman ,  Age ： 23 stay edu School  */
  // Be careful ： The access permission of the method overridden in the subclass must not be lower than that of the method overridden by the parent class .
  // For example, the access permission of the method in the parent class is protected, Then the access permission of the method overridden in the subclass is protected perhaps public

?>