Php code – Codemeets – 05
PHP CodeMeets 5: Classes, Constructor, Objects, Getter/Setters, and Inheritance
php codemeets In this lesson, we will focus on the core concepts of Object-Oriented Programming (OOP) in PHP. These concepts will help you organize your code, making it more reusable, modular, and maintainable.
What is a Class in PHP?
A class is a blueprint for creating objects in object-oriented programming. A class is a collection of objects and functions (also called methods) that operate on data contained within the objects.
Classes help organize code and promote reusability. Once a class is defined, you can create multiple objects (instances) of that class, each having its own properties and behaviors.
Declaring and Using a Class in PHP
Key Concepts
You can access methods of an object using the -> operator.
Here’s an example to demonstrate how to declare a class and use it:
Class Declaration:
A class is declared using the class keyword, followed by the class name.
Inside the class, we define properties (variables) and methods (functions).
Constructor:
The constructor is a special function called automatically when an object is created. It is used to initialize the properties of an object.
The constructor is defined using function __construct().
Creating Objects:
An object is created by using the new keyword followed by the class name.
The constructor is called when the object is created, and values are passed to initialize the properties.
Accessing Object Methods:
<?php
class Book {
var $name;
var $author;
var $price; //class assing
}
$book1 = new book;
$book1 = name = "Harry Potter";
$book1 = price = "1700"; //make objects
$book1 = author = "JK";
echo $book1 -> name;
echo $book1 -> price;
?>This code output is Harry Potter 1700.
Constructor
In class-based object-oriented programming (OOP), a constructor is a special method that is automatically called when an object of a class is created. Its primary purpose is to initialize the newly created object, often by setting initial values for the object’s properties.
A constructor can accept arguments, which are used to initialize the object’s member variables or perform other setup tasks. The constructor method is named
__construct()in PHP.
You can get good idea using following example about php constructor.
<?php
class Book{
var $name;
var $price;
var $author;
function__construct(){
echo"this is book<br>";
}
}
$book1 = new Book;
$book2 = new Book;
?>
This code output is This is book two time print.
Object and Functions
In computer programming, a function object (also known as a functor) is an object that can be called or invoked as if it were a regular function. This concept allows objects to be treated like functions, and they can be passed around, stored, or invoked in places where functions are typically used.
Function objects are often used in programming languages that support object-oriented principles, such as C++, Python, and PHP. The primary benefit is that they allow behavior (functions) to be encapsulated within objects, which can carry additional state or data, making them more flexible than regular functions.
Key Features of Function Objects (Functors):
Flexibility: They allow a combination of data and functionality within a single object, making the code more modular and reusable.
Callable Syntax: Function objects can be invoked using the same syntax as calling a regular function, i.e., using parentheses
()to pass arguments and get a result.Encapsulation: Function objects can store additional state or data that may be useful for the operation they perform.
This is mining of the object and functions. now we can try to add it php. look below example.
<?php
class student {
var $name;
var $stream;
var $gpa;
function__construct ($name,$stream,$gpa){
$this->name = $name;
$this->stream = $stream;
$this->gpa = $gpa;
}
function hasHonors(){
if ($this->gpa>2.5){
return "true";
}
else{
return "false";
}
}
}
$student1 = new student ("jane","Maths","3.2");
$student2 = new student ("mick","Biology","2.4");
echo $student1 -> hasHonors();
echo $student2 -> hasHonors();
?>This code answer is true false.
Getters and Setters
get create function function getRating(){}
use if statement function setRating($rating)
Private can not be change. Public can be change.
Inheritance
In Object-Oriented Programming (OOP), inheritance is a core concept that allows a class (called a subclass or derived class) to inherit properties and methods from another class (called a superclass or base class). This mechanism enables code reuse, modularity, and the creation of a class hierarchy, where a subclass can be built upon the existing functionality of a superclass.
Key Points of Inheritance:
Class Hierarchy: Classes can be organized into a hierarchy, where subclasses inherit characteristics and behavior from their parent classes.
Reusability: Inheritance allows a subclass to reuse the code from the superclass, meaning you don’t need to rewrite common functionality.
Extensibility: A subclass can extend the functionality of the superclass by adding new properties and methods or overriding existing ones.
see below you can get idea for inheritance.
<?php
class chef{
function makechicken(){
echo "make chicken";
}
function make salad(){
echo "make salad";
}
function make bbq(){
echo "make bbq";
}
}
$italianchef = new italianchef;
echo $italiancheff->makechicken();
echo $italiancheff->makebbq();
?>
output is make chicken and make bbq.
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