PHP Classes and Objects Examples

PHP object-oriented programming examples including classes, objects, inheritance, and methods.

Define a class and an object

                
                    <?php
                    class Fruit {
                      // Properties
                      public $name;
                      public $color;
                    
                      // Methods
                      function set_name($name) {
                        $this->name = $name;
                      }
                      function get_name() {
                        return $this->name;
                      }
                    }
                    
                    $apple = new Fruit();
                    $banana = new Fruit();
                    $apple->set_name('Apple');
                    $banana->set_name('Banana');
                    
                    echo $apple->get_name();
                    echo "<br>";
                    echo $banana->get_name();
                    ?>
                
                

Using the $this keyword

                
                    <?php
                    class Fruit {
                      public $name;
                      function set_name($name) {
                        $this->name = $name;
                      }
                    }
                    $apple = new Fruit();
                    $apple->set_name("Apple");
                    
                    echo $apple->name;
                    ?>
                
                

Using the instanceof keyword

                
                    <?php
                    class Fruit {
                      // Properties
                      public $name;
                      public $color;
                    
                      // Methods
                      function set_name($name) {
                        $this->name = $name;
                      }
                      function get_name() {
                        return $this->name;
                      }
                    }
                    
                    $apple = new Fruit();
                    var_dump($apple instanceof Fruit);
                    ?>
                
                

Creating a constructor

                
                    <?php
                    class Fruit {
                      public $name;
                      public $color;
                    
                      function __construct($name) {
                        $this->name = $name; 
                      }
                      function get_name() {
                        return $this->name;
                      }
                    }
                    
                    $apple = new Fruit("Apple");
                    echo $apple->get_name();
                    ?>
                
                

Creating a destructor

                
                    <?php
                    class Fruit {
                      public $name;
                      public $color;
                    
                      function __construct($name) {
                        $this->name = $name; 
                      }
                      function __destruct() {
                        echo "The fruit is {$this->name}."; 
                      }
                    }
                    
                    $apple = new Fruit("Apple");
                    ?>
                
                

Inheritance

                
                    <?php
                    class Fruit {
                      public $name;
                      public $color;
                      public function __construct($name, $color) {
                        $this->name = $name;
                        $this->color = $color; 
                      }
                      public function intro() {
                        echo "The fruit is {$this->name} and the color is {$this->color}."; 
                      }
                    }
                    
                    // Strawberry is inherited from Fruit
                    class Strawberry extends Fruit {
                      public function message() {
                        echo "Am I a fruit or a berry? "; 
                      }
                    }
                    
                    $strawberry = new Strawberry("Strawberry", "red");
                    $strawberry->message();
                    $strawberry->intro();
                    ?>
                
                

Class constants

                
                    <?php
                    class Goodbye {
                      const LEAVING_MESSAGE = "Thank you for visiting W3Schools.com!";
                    }
                    
                    echo Goodbye::LEAVING_MESSAGE;
                    ?>
                
                

Abstract classes

                
                    <?php
                    // Parent class
                    abstract class Car {
                      public $name;
                      public function __construct($name) {
                        $this->name = $name;
                      }
                      abstract public function intro() : string; 
                    }
                    
                    // Child classes
                    class Audi extends Car {
                      public function intro() : string {
                        return "Choose German quality! I'm an $this->name!"; 
                      }
                    }
                    
                    class Volvo extends Car {
                      public function intro() : string {
                        return "Proud to be Swedish! I'm a $this->name!"; 
                      }
                    }
                    
                    class Citroen extends Car {
                      public function intro() : string {
                        return "French extravagance! I'm a $this->name!"; 
                      }
                    }
                    
                    // Create objects from the child classes
                    $audi = new audi("Audi");
                    echo $audi->intro();
                    echo "<br>";
                    
                    $volvo = new volvo("Volvo");
                    echo $volvo->intro();
                    echo "<br>";
                    
                    $citroen = new citroen("Citroen");
                    echo $citroen->intro();
                    ?>
                
                

Traits

                
                    <?php
                    trait message1 {
                      public function msg1() {
                        echo "OOP is fun! "; 
                      }
                    }
                    
                    class Welcome {
                      use message1;
                    }
                    
                    $obj = new Welcome();
                    $obj->msg1();
                    ?>
                
                

Static method

                
                    <?php
                    class greeting {
                      public static function welcome() {
                        echo "Hello World!";
                      }
                    }
                    
                    // Call static method
                    greeting::welcome();
                    ?>
                
                

Static property

                
                    <?php
                    class pi {
                      public static $value = 3.14159;
                    }
                    
                    // Get static property
                    echo pi::$value;
                    ?>