Php Object Oriented

protected //like private but only the subclass can change the values.

public //any code can change this attributes.

private //only method and function can change this data.

class Animal {

    protected $name;
    protected $favorite_food;
    protected $sound;
    protected $id;

//Like any other PHP static variable, static properties may only be initialized using a literal or constant before PHP 5.6; expressions are not allowed. 

//In PHP 5.6 and later, the same rules apply as const expressions: some limited expressions are possible, provided they can be evaluated at compile time. 

    public static $number_of_animals = 0;

    const PI = "3.14159"; // never change is value

    function getName(){ // encapsulate / protect change the data.

        return $this->name; // refers to the current class.
// if there is $name in this function, "this" will refer to the function.
    }

// Constructor - initialize things / set some value.

    function __construct() {
        $this->id = rand(100,1000000); //set a random number between 100 - 1 million.
        
        echo $this->id . " has been assigned<br>";

        Animal::$number_of_animals++; //access the static for $number_of_animals .

    }
}

Getter and Setters

class Person{
    
    //The name of the person.
    private $name;
    
    //The person's date of birth.
    private $dateOfBirth;
    
    //Set the person's name.
    public function setName($name){
        $this->name = $name;
    }
    
    //Set the person's date of birth.
    public function setDateOfBirth($dateOfBirth){
        $this->dateOfBirth = $dateOfBirth;
    }
    
    //Get the person's name.
    public function getName(){
        return $this->name;
    }
    
    //Get the person's date of birth.
    public function getDateOfBirth(){
        return $this->dateOfBirth;
    }

    //For Override class
    function run() {
     echo $this->name . " runs<br>";
}

//Set new person
$person = new Person();
 
//Set the name to "Dov"
$person->setName('Dov');
 
//Get the person's name.
$name = $person->getName();
 
//Print it out
echo $name;


//Set person with if statement.
//-----------------------------

//Set the person's name.
public function setName($name){
   if(!is_string($name)){
       throw new Exception('$name must be a string!');
   }
   $this->name = $name;
}

Extends / Enarate

class Dog extends Animal {
//We override it on the next code section (on Extends / Enarate).
    function run() {
     echo $this->name . " runs like crazy<br>"; //we overwrite this function 
 }