PHP OOP : Static Members

What is Static Members ?

  • Static properties and methods can be used without creating an instance of the class.
  • The static keyword is used to declare properties and methods of a class as static.
  • Object not create.
  • Stack keyword use before access modifier.
  • Inside class use self::(use static method).
  • inherit use parent class name ::(properties).

Example :

Example Constructor :-

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PHP OOP : Interfaces

What is Interfaces?

  • Interfaces help us to use multiple classes in a single class inherit.
  • Interfaces are declared with the interface keyword.
  • Derived class is called derived class.
  • object not be created in interface.
  • Property should not be defined in interface(class).
  • All interface methods must be public.
  • All methods in an interface are abstract.
  • To implement an interface, a class must use the implements keyword.

Example :-

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PHP OOP : Abstract Classes

Abstract Class :

  • when we create abstract class then we can not create object of that abstract class.
  • If we want to use abstract class then we only access with derived class .
  • Just abstract write before the class name.
  • when we create abstract class two condition occurs one is abstract method like :- abstract protected function name ( );
  • abstract means incomplete method we declare but not implement (code).
  • In derived class we have to implement of that abstract method.
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PHP OOP : Overriding properties and Methods

Overriding Properties :

  • Same properties on both classes (base and derived class).

Overriding Methods :

  • Same name of method on both classes base or derived class.
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PHP OOP : Access Modifier (public, protected, private)

What is the access modifier?

Restrictions on properties and methods.

Types of access modifier

  1. public
  2. protected
  3. private

Public :

  • Access on base as well as derived class and outside of the class.
  • Everyone can see and access the data.
  • Not secure.
  • Override use.

Protected :

  • Base and Derived class.
  • No one gets access throughout the class.
  • Declare like protected property and method.
  • Not use override function.
  • Without permission no one can access any of these (properties & method).

Private :

  • Access itself.
  • Highly secured.
  • No one can access without permission.
  • Highly costly.
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PHP OOP : Inheritance

What is inheritance in php?

  • Inheritance is properties of PHP.
  • Accessing the feature of one class of another class.
  • Three types that is single, multiple and multilevel inheritance.
  • It is the four pillars of oops.
  • It allows a class to reuse the code from another class without duplicating it.
  • Two classes one is base/main another one is derived class.
  • Base class only use its own function but in Derived class it use both function base or derived class.

How to use inheritance in php?

class school {
}
class students extends school {
}
$sch =new school (); // only use class school 
$stu = new students (); // use both class school students (properties and methods)

Example of main/base class use :-

Example of inheritance:

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PHP OOP : Constructor function

What is Constructor ?

Constructor is a special type of function of a class which is automatically executed when object of that class is created. Constructor is also called as magic function because in php constructor is start usually with two underscore characters. It saves lot of time on big project.

function __constructor(){
body part;
}

Example of Constructor :-

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Introduction to PHP OOP

What is PHP?

  • PHP stands for hypertext preprocessor.
  • It is widely used in backend programming language.
  • PHP programming patterns are procedural/core php and object oriented.
  • Lots of framework are use like laravel, CakePHP, Yii, Zend, Codeigniter etc.
  • Code more modular and reusable.
  • Well organised code.
  • Easier to debug.
  • Best for large website projects.

Why is it so popular ?

  • Code reusable
  • Easier to debug
  • Best for medium and large website project
  • Backend programming use
  • Code more modular
  • Understanding code easier

What are class and object ?

  • Class are the blueprint of object ; Object use blueprint to build their project or functions.
  • Class example :- blueprint of house ; Object example :- built house.
  • Class function one ; Object function are lots that are related to class function.
  • If there is a function which is written in object but not written in class then that function will not work.

What is properties and methods ?

properties like :-

$a;
$b;
$c;
$d;

Methods like :-

sum(){
$c=$a+$b;
return $c;
}

Example of PHP :-

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JavaScript : Advantages and disadvantages of External JavaScript ?

Advantages :

Following are the Advantages of javaScript over external :-

  • Reusability of code.
  • Easy code readability.
  • It Enables both web designers and coders to work with html and js files.
  • With these small js files, you can use Google closure or YUI Compressor or other minifying tools to reduce the size and make it not readable by humans .

Disadvantages :

Following are the disadvantages of javaScript over external :-

  • Code can be downloaded using the url of the js file. This can help coders to steal your code easily.
  • If two js files are dependent on one another, then a failure in one file may affect the execution of the other dependent file.
  • A small change to a common js file may cause unexpected results in some of the HTML files .
  • The browser has to make an extra http request to get the js code.
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JavaScript : Where to use javaScript code

JavaScript code use in following :

  1. Between the body tag of html
  2. Between the head tag of html
  3. In .js file (external javaScript)

1. JavaScript use between html body tag :

Example of javaScript using inside html between body tag.

Output :- Hello World

2. JavaScript use between head tag in html :

Example to use javaScript between head tag in html.

Output :

3. External JavaScript file :

We can create external JavaScript file and embed it in many html page. If you want to run the same JavaScript on several pages in a web site, you should create an external JavaScript file, instead of writing the same script over and over again.

message.js

index.html

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