Slide môn học PHP session 8b OOP concepts

OOP Concepts Session 21 Review     Functionality of the email process is done with the help of the mail() function Main arguments of the mail() function are:  Recipient’s email address  Subject of the email  Body of the email Local mail server for mail() function is specified in the php.ini configuration file Type of messages are specified with the help of the content-type header while attaching a file to the email PHP / Session 21 / Slide of 23 Objectives  Discuss Object Oriented Basics  Use Inheritance  Use Classes  Use Constructors  Create and Use Objects PHP / Session 21 / Slide of 23 Object Oriented Basics    Programming with a data type of a data structure that is defined with the type of functions and are performed on the data structure Uses for combining the data and the functions into a single unit or an object Concept of an object-oriented programming are:  Objects  Class  Abstraction  Encapsulation  Polymorphism  Inheritance PHP / Session 21 / Slide of 23 Inheritance - I     Creates a new class with the help of a base class Properties such as variables, functions, and methods of the base class are transferred to the newly derived class Uses the extends keyword for inheriting a new class from the base class Derived class also has its own variables and functions PHP / Session 21 / Slide of 23 Inheritance - II  Types of inheritances are:      Single inheritance Multiple inheritance Hierarchical inheritance Multilevel inheritance Hybrid inheritance Note: In PHP, multiple inheritances are not supported PHP / Session 21 / Slide of 23 Class     Object that contains variables and functions of different data types is a class Class can be inherited from a base class to create a new derived class Derived class uses all the properties of the base class including its own properties Class variables are local to its class PHP / Session 21 / Slide of 23 Declaring a Class  Syntax for declaring a class is: class class_name { var class_variable; function function_name() } Where,      class – Uses for declaring a class name class_name – Specifies the class name class_variable – Specifies the variable name for the class function – Uses for defining a function function_name() – Specifies the function name PHP / Session 21 / Slide of 23 Class - Example- I  For example, to enter the employee details using classes PHP / Session 21 / Slide 10 of 23 Saving the Class file   Saves the file as empdet.inc and includes it in the php file Includes the empdet.inc file in the php file in the following format: include “empdet.inc”; PHP / Session 21 / Slide 11 of 23 Inheriting a Class   A new class can be inherited from an old class A new class uses the properties of the parent class along with its own properties PHP / Session 21 / Slide 12 of 23 Syntax for Inheriting a Class  Syntax for inheriting a new class is: class class_name { var class_variable; function function_name() } class new_class extends class_name { var class_variable; function function_name() } PHP / Session 21 / Slide 13 of 23 Inheritance - Example - I  Derive a gross_salary class from the salary class PHP / Session 21 / Slide 15 of 23 Constructors    Function that has the same name as that of its class name is a constructor Uses new operator for calling constructor in the main program That is creating a request for the class Provides values to all the objects of the class when a constructor is declared PHP / Session 21 / Slide 16 of 23 Creating a Constructor  Syntax for creating a constructor is: class class_name { var class_variable; function constructor_name() } Where,      class – Uses for declaring a class name class_name – Specifies the class name class_variable – Specifies the variable name for the class function – Uses for defining a function constructor_name() – Specifies the function name that is same as the class name PHP / Session 21 / Slide 17 of 23 Constructor - Example - I  For example, to call a constructor from a derived class from a base class PHP / Session 21 / Slide 19 of 23 Create and Use Objects      Self-contained entity those consists of both data and procedures to manipulate the data It is an instance of a class Uses for maintaining the codes in the program Objects can be manipulated as needed Provides values to all the objects of the class when a constructor is declared Gives reference to a class There can be more than one object for a single class Uses the new operator to initialize the object PHP / Session 21 / Slide 20 of 23 Creating an Object  Syntax for creating an object is: class class_name { var class_variable; function function_name() } $object_name = new class_name; Where,    object_name – Specifies the name of object new – Initializes the object class_name – Specifies the class name the PHP / Session 21 / Slide 21 of 23 Creating an Object - Example  For example, create an object for the class usermail PHP / Session 21 / Slide 22 of 23 Summary       OOP is a programming language model, made up of objects and data Objects can be manipulated as needed Main characteristics of an OOP are objects, class, abstraction, encapsulation, polymorphism, and inheritance Class is an object that can be inherited from a base class to a derived class It has its own properties Deriving a new class from a parent class or a base class is termed as inheritance It is done with the help of the extends keyword Function that has the same name as that of its class name is a constructor It is called by using a new operator Object is an instance of a class It gives a reference to the class PHP / Session 21 / Slide 23 of 23 [...]... Saves the file as empdet.inc and includes it in the php file Includes the empdet.inc file in the php file in the following format: include “empdet.inc”; PHP / Session 21 / Slide 11 of 23 Inheriting a Class   A new class can be inherited from an old class A new class uses the properties of the parent class along with its own properties PHP / Session 21 / Slide 12 of 23 Syntax for Inheriting a Class  Syntax... new_class extends class_name { var class_variable; function function_name() } PHP / Session 21 / Slide 13 of 23 Inheritance - Example - I  Derive a gross_salary class from the salary class < ?php class salary { function sal_hra($basic) { return $basic * 0.25; } function sal_ta($basic) { return $basic * 0.08; } PHP / Session 21 / Slide 14 of 23 Inheritance - Example - II function sal_pf($basic) { return... function name that is same as the class name PHP / Session 21 / Slide 17 of 23 Constructor - Example - I  For example, to call a constructor from a derived class from a base class < ?php class string { function string() { echo “This function is made a constructor.”; } function stringdisp() { echo “This is an example for constructor.”; } } PHP / Session 21 / Slide 18 of 23 Constructor - Example - II class... $basic + ($hra + $ta) - $pf; } } ?> PHP / Session 21 / Slide 15 of 23 Constructors    Function that has the same name as that of its class name is a constructor Uses new operator for calling constructor in the main program That is creating a request for the class Provides values to all the objects of the class when a constructor is declared PHP / Session 21 / Slide 16 of 23 Creating a Constructor... operator to initialize the object PHP / Session 21 / Slide 20 of 23 Creating an Object  Syntax for creating an object is: class class_name { var class_variable; function function_name() } $object_name = new class_name; Where,    object_name – Specifies the name of object new – Initializes the object class_name – Specifies the class name the PHP / Session 21 / Slide 21 of 23 Creating an Object -... < ?php class usermail { var $username = “john”; var $password = “abc123”; } class userdetails extends usermail { var $secretquery = “favourite food”; var $answer = “chinese”; } $mail = new userdetails; echo $mail; ?> PHP / Session 21 / Slide 22 of 23 Summary       OOP is a programming language model, made up of objects and data Objects can be manipulated as needed Main characteristics of an OOP. .. 21 / Slide 18 of 23 Constructor - Example - II class display extends string { function displaystring() { echo “This is a new class and a new function”; } } $disp = new display; echo $disp; ?> PHP / Session 21 / Slide 19 of 23 Create and Use Objects      Self-contained entity those consists of both data and procedures to manipulate the data It is an instance of a class Uses for maintaining the codes... extends keyword Function that has the same name as that of its class name is a constructor It is called by using a new operator Object is an instance of a class It gives a reference to the class PHP / Session 21 / Slide 23 of 23