Classes (PHP)
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PHP is an object oriented programming language. This article is an introduction to classes and object oriented programming. It's not very PHP-specific.
Classes
In PHP, a "class" is a blueprint or template for creating objects. It defines a set of properties (variables) and methods (functions) that the objects created from the class will have. Classes are a fundamental concept in object-oriented programming (OOP), and they are used to model real-world entities and encapsulate data and behavior related to those entities:
- Objects: Objects are instances of a class. You can create multiple objects from the same class, and each object will have its own set of properties and methods defined by the class
- Properties: Properties (also known as member variables or attributes) are variables associated with a class. They store the data that represents the state of an object. Each object has its own copy of the class's properties
- Methods: Methods are functions defined within a class. They encapsulate the behavior or actions that objects created from the class can perform. Methods can operate on the class's properties and interact with other objects
- Encapsulation: Classes provide a way to encapsulate data and behavior. This means that the internal details of how a class works are hidden from the outside, and access to properties and methods is controlled through visibility modifiers (e.g., public, private, protected)
- Inheritance: PHP supports inheritance, which allows you to create a new class that inherits properties and methods from an existing class. This promotes code reuse and allows you to create specialized classes based on more general ones
- Polymorphism: Polymorphism is the ability to use different classes or objects in a consistent way. In PHP, this is often achieved through interfaces and abstract classes.
Example
################################################################### # Class definition ################################################################### # class Person{ # # Define properties ######################################## # public $name; public $age; # Define constructor method ######################################## # public function __construct($name, $age) { $this->name = $name; $this->age = $age; } # Define method "introduce()" ######################################## # public function introduce() { echo "Hi, I'm {$this->name} and I'm {$this->age} years old."; } } ################################################################### # Main script ################################################################### # # # Create an object from the class ######################################## # $person1 = new Person("Alice", 30); # Call "introduce()" method ######################################## # # Output: Hi, I'm Alice and I'm 30 years old. # $person1->introduce();
Get methods
Example get_class_methods
[1]:
$sql="show databases;"; $result = $conn->query($sql); print_r(get_class_methods($conn));
Get properties
Voorbeeld get_objects_vars
[2]:
sql="show databases;"; $result = $conn->query($sql); print_r(get_object_vars($conn));