PHP implements the method of accessing its private attribute private and its protection attribute protected outside the object

This article illustrates how PHP can access its private attribute private and its protected attribute protected outside of an object. Share it for your reference, as follows:

public represents global access rights, which can be accessed by internal and external subclasses of the class;
private denotes private access rights, which can only be used inside this class;
protected denotes protected access rights that can be accessed only in this class or subclass or parent class;

Examples of more classic usage are as follows:

<?php
 // Parent class 
 class father{
 public function a(){
 echo "function a<br/>";
 }
 private function b(){
 echo "function b<br/>";
 }
 protected function c(){
 echo "function c<br/>";
 }
 }
 // Subclass 
 class child extends father{
 function d(){
 parent::a();// Call the parent class's a Method 
 }
 function e(){
 parent::c(); // Call the parent class's c Method 
 }
 function f(){
 parent::b(); // Call the parent class's b Method 
 }
 }
 $father=new father();
 $father->a();
// $father->b(); // Display error   Private methods cannot be called externally  Call to protected method father::b()
// $father->c(); // Display error   Protected methods cannot be called externally Call to private method father::c()
 $chlid=new child();
 $chlid->d();
 $chlid->e();
// $chlid->f();// Display error   Unable to call parent class private Method of  Call to private method father::b()
?>

Run results:

function a
function a
function c

Outside objects, php accesses private and protected properties as follows:

class yunke
{
 protected $a = 55;
 private $b = 66;
 public function merge()
 {
 $result = clone $this;
 $result->a=88;
 $result->b=99;
 return $result;
 }
 public function show()
 {
 echo $this->a;
 echo $this->b;
 }
}
$test = new yunke;
$test->show();
$test2=$test->merge();
$test2->show();

Output:

55668899

For more readers interested in PHP related content, please check the topics on this site: "Introduction to php Object-Oriented Programming", "Encyclopedia of PHP Array (Array) Operation Skills", "Introduction to PHP Basic Syntax", "Summary of PHP Operation and Operator Usage", "Summary of php String (string) Usage", "Introduction to php+mysql Database Operation" and "Summary of php Common Database Operation Skills"

I hope this article is helpful to everyone's PHP programming.