PHP Object Oriented Programming পর্ব-৬: PHP OOP Inheritance

<?php
class ParentClass {
  // properties and methods here
}
 
class ChildClass extends ParentClass {
  // additional properties and methods here
}
?>

<?php
class Member {
  public $username = "";
  private $loggedIn = false;
  public function login() {
    $this->loggedIn = true;
  }
  public function logout() {
    $this->loggedIn = false;
  }
  public function isLoggedIn() {
    return $this->loggedIn;
  }
}
?>

<?php
class Administrator extends Member {
  public function createForum( $forumName ) {
    echo "$this->username created a new forum: $forumName<br>";
  }
  public function banMember( $member ) {
    echo "$this->username banned the member: $member->username<br>";
  }
}
?>

<?php
class Member {
    public $username = "";
    private $loggedIn = false;
    public function login() {
        $this->loggedIn = true;
    }
    public function logout() {
        $this->loggedIn = false;
    }
    public function isLoggedIn() {
        return $this->loggedIn;
    }
}
 
class Administrator extends Member {
    public function createForum( $forumName ) {
        echo "$this->username created a new forum: $forumName<br>";
    }
    public function banMember( $member ) {
        echo "$this->username banned the member: $member->username<br>";
    }
}
 
// Create a new member and log them in
$member = new Member();
$member->username = "Sahab Uddin";
$member->login();
echo $member->username . " is " . ( $member->isLoggedIn() ? "logged in" : "logged out" ) . "<br>";
 
// Create a new administrator and log them in
$admin = new Administrator();
$admin->username = "Mahmudur";
$admin->login();
echo $admin->username . " is " . ( $member->isLoggedIn() ? "logged in" : "logged out" ) . "<br>";
// Displays "Mary created a new forum: INNOVA Computers BD"
$admin->createForum( "INNOVA Computers BD" );
// Displays "Mahmudur banned the member: Sahab Uddin"
$admin->banMember( $member );
?>

<?php
/**
Check User Exist or Not
*/
class Member 
{
    protected $isLoggedIn=false;
    protected $role;
    protected $users=[
        ["username"=>"abc","password"=>"xyz","role"=>"subscriber"],
        ["username"=>"acb","password"=>"yxz","role"=>"admin"],
        ["username"=>"bca","password"=>"zxy","role"=>"super_admin"]
    ];
    public function Login($user,$pass){
         
 
        foreach($this->users as $user_info){
            extract($user_info);
             
            if($username==$user && $password==$pass){
                $this->isLoggedIn=true;
                $this->role=$role;
            }
        }
    }
}
 
/**
* Child Class Check User Role
**/
class Role extends Member
{
     
    function __construct($user,$pass)
    {
        $this->Login($user,$pass);
            if($this->isLoggedIn){
                if($this->role=='subscriber'){
                    echo "You're Logged in as a Subscriber";
                }
                if($this->role=='admin'){
                    echo "You're Logged in as a Administrator";
                }
 
                if($this->role=='super_admin'){
                    echo "You're Logged in as a Super Administrator";
                }
            }
            else{
                    echo "Invalid Username/Password";
                }
 
    }
}
 
$login=new Role("acb","yxz");

class ParentClass {
  public function myMethod($x) {
    // (method code here)
  }
}
class ChildClass extends ParentClass {
  public function myMethod($x) {
    // For ChildClass objects, this method is called
    // instead of the parent class's MyMethod()
  }
}

<?php
class Member {
  public $username = "";
  private $loggedIn = false;
  public function login() {
    $this->loggedIn = true;
  }
  public function logout() {
    $this->loggedIn = false;
  }
}
class Administrator extends Member {
  public function login() {
    $this->loggedIn = true;
    echo "Log entry: $this->username logged in<br>";
  }
}
// Create a new member and log them in
$member = new Member();
$member->username = "Sahab Uddin";
$member->login();
$member->logout();
// Create a new administrator and log them in
$admin = new Administrator();
$admin->username = "Mahmudur";
$admin->login();           // Displays "Log entry: Mahmudur logged in"
$admin->logout();

parent::parentMethod();

<?php
class Member {
  public $username = "";
  private $loggedIn = false;
  public function login() {
    $this->loggedIn = true;
  }
  public function logout() {
    $this->loggedIn = false;
  }
}
class Administrator extends Member {
  public function login() {
    parent::login(); // Using parent keyword
    echo "Log entry: $this->username logged in<br>";
  }
}
// Create a new member and log them in
$member = new Member();
$member->username = "Sahab Uddin";
$member->login();
$member->logout();
// Create a new administrator and log them in
$admin = new Administrator();
$admin->username = "Mahmudur";
$admin->login();           // Displays "Log entry: Mahmudurlogged in"
$admin->logout();

<?php
class Member {
  public $username = "";
  private $loggedIn = false;
  public final function login() {
    $this->loggedIn = true;
  }
  public function logout() {
    $this->loggedIn = false;
  }
  public function isLoggedIn() {
    return $this->loggedIn;
  }
}
 
class NaughtyMember extends Member {
  public function login() {
    $this->loggedIn = true;
    // Do something bad
  }
}
?>

<?php
final class Member {
  // This class can't be extended at all
}
class Administrator extends Member{
// Will show Fatal Error
}
?>