1. Classes & Objects
There are two main programming paradigms: Procedural Object-Oriented Up to now, everything we have done has been procedural.

2. Procedural Programming
A list of instructions to carry out step-by-step Programs execute from the top down, line by line Programs can rely heavily on functions & other procedures (conditionals, loops)

3. You should have a good understanding of: variables operators conditionals (if statements) loops functions

4. Object-Oriented Programming
OOP - all computations are based on objects Objects are instances of Classes For example, a dog named Rover is an object of the dog class A class is a blueprint or template for making objects

5. Example Person Class class Person { private $first; private $last;
private $age; }
Class with 3 properties (variables)
private scope of property – only visible in this class

6. Class Scope 3 identifiers for class properties (variables)
and methods (functions)
public – visible outside the class
protected - visible to any inherited class
private – visible only inside that class

7. Magic Constructor Method
class Person {
private $first;
private $last;
private $age;
public function __construct($first,
$last, $age) {
$this->first = $first;
$this->last = $last;
$this->age = $age; }

8. new Object $obj = new Person();
Automatically calls magic constructor method
public function __construct()
(notice double underscore)

9. public function __construct($first,
$last, $age) {
$this->first = $first;
$this->last = $last;
$this->age = $age; }
Special variable $this refers to current object
Object operator -> points to class properties & methods
Class property references ->age do not use $

10. Class with New Object class Person {
private $first;
private $last;
private $age;
public function __construct($first,
$last, $age) {
$this->first = $first;
$this->last = $last;
$this->age = $age; }
$obj = new Person($first, $last, $age);

11. Inheritance Classes may inherit from other classes class Mammal {
protected $vertebra; }
class Tiger extends Mammal {
protected $stripes;
public function __construct($vertebra,
$stripes) {
Mammal::__construct($vertebra);
$this -> stripes = $stripes;

12. :: Scope Resolution Operator
Use the scope resolution operator :: to access
properties and methods outside the class.
public function __construct($vertebra,
$stripes) {
Mammal::__construct($vertebra);