How to create abstract classes and methods

An abstract class with an abstract method

      abstract class Person { 
        private $firstName, $lastName, $phone, $email;

        // The constructor and the get and set methods are the same as the Person class

        // An abstract method 
        abstract public function getFullName();
      }

A concrete class that implements an abstract class

      class Customer extends Person {
        private $cardNumber, $cardType;

        public function __construct($first, $last, $phone, $email) {
          $this->setPhone($phone);
          $this->setEmail($email);
          parent::__construct($first, $last);
        } 
        
        public function getCardNumber() {
          return $this->cardNumber; 
        } 
        
        public function setCardNumber($value) {
          $this->cardNumber = $value; 
        } 
        
        public function getCardType() {
          return $this->cardType; 
        }
        
        public function setCardType($value) { 
          $this->cardType = $value; 
        } 
        
        // Concrete implementation of the abstract method 
        public function getFullName() {
          return $this->getFirstName() . ' ' . $this->getLastName(); 
        } 
      }

Code that attempts to create an object from the abstract class

      $customer = new Person('John', 'Doe'); // Fatal error

Code that creates and uses an object from the concrete

       class $customer = new Customer('John', 'Doe', '919-555-4321', 'jdoe@example.com');
       echo("<p>" .$customer->getFullName() . "</p>");

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