OOP In PHP | Object Oriented Programming In PHP | PHP Tutorial For Beginners | Simplilearn

[00:08] hello everyone i am anish from simply

[00:10] learn and welcome to the video on object

[00:13] oriented programming in php

[00:15] in this video we will discuss everything

[00:18] about oops concept in detail

[00:20] but before that let me tell you

[00:23] according to indeed.com the demand for

[00:25] php developers has massively increased

[00:28] to 835 percent since january 2020

[00:33] however in today's market it is the

[00:35] fastest growing tech job across the

[00:37] industry

[00:39] so in today's video we'll be discussing

[00:42] what is php what are the concepts of

[00:44] oops in php and finally we will have a

[00:47] look at the demo where we will be

[00:49] executing the code that has class

[00:51] objects inheritance and polymorphism in

[00:54] it

[00:55] now comes the important question what

[00:58] exactly is php

[01:01] so we have spoken a lot about it so far

[01:03] but do you know what it means

[01:05] well php stands for hypertext

[01:08] preprocessor

[01:09] it is a server-side scripting language

[01:11] that is embedded into html and used for

[01:14] developing dynamic websites

[01:17] now let's move ahead and understand the

[01:19] concepts of oops in php

[01:22] so as you can see on the screen i have

[01:24] listed down the eight concepts of oops

[01:27] that we will be discussing today

[01:29] first is class

[01:31] next comes objects then its member

[01:33] function and member variables then

[01:36] constructor and destructor

[01:38] inheritance and finally it is

[01:40] polymorphism

[01:42] now let's walk through each of the

[01:44] concepts one by one

[01:46] first is class

[01:48] it is a blueprint of an object that

[01:50] provides initial values for the state a

[01:54] class consists of both data and

[01:56] functions and data and functions

[01:57] together are called objects

[02:00] now let's first have a look at the class

[02:04] let me create a file

[02:06] named class dot php

[02:10] and let us write the code first

[02:52] um

[03:05] okay

[04:04] here i have defined a class by using the

[04:06] class keyword

[04:07] followed by fruit which is the class

[04:10] name

[04:11] next i have added a pair of curly braces

[04:14] and added the entire properties and

[04:16] methods within the braces so as you can

[04:19] see on the screen we have declared a

[04:21] class named fruit

[04:23] that contains two properties called name

[04:26] and color

[04:27] along with that i have also added two

[04:29] methods set name and get name

[04:34] now now the purpose of these methods is

[04:36] for setting and getting the name

[04:39] property

[04:40] so let me give you some in important

[04:42] information so when you define a class a

[04:45] variable in it is called property while

[04:48] a function is known as method

[04:51] now let us execute the code and see the

[04:53] output

[04:57] let's go to the browser

[04:59] and type localhost followed by the file

[05:02] name

[05:08] here here's a file class.php

[05:11] and as you can see on the screen

[05:13] the code is running perfectly

[05:16] now that was about the class

[05:19] next comes objects

[05:21] so it is an instance of a class

[05:23] basically

[05:25] a variable holds a date of a class

[05:27] now we define a class once

[05:31] and create as many objects in it

[05:34] for a better understanding let me give

[05:36] you an example

[05:37] suppose a car is a class so

[05:40] mercedes-benz and bmw would be objects

[05:43] now let's see objects

[05:45] classes are incomplete without objects

[05:48] so we can add as many objects as we want

[05:51] from a class

[05:52] and every single object has the

[05:55] properties and methods defined in the

[05:57] class but those objects will have

[05:59] different property values

[06:01] so objects of a class are created using

[06:04] the new keyword

[06:06] now let me open the code editor

[06:10] and let's create another file

[06:13] called

[06:14] obj.php

[06:18] so this code will be the same

[06:21] let's copy

[06:23] and paste it here

[06:28] now let me type the code for object

[06:33] [Music]

[06:41] as you can see i have used the new

[06:43] keyword to create object of the class

[06:46] fruit

[06:51] similarly

[06:56] banana

[06:57] would be another object

[07:11] and now we'll use the set name function

[07:16] to set

[07:17] the name to apple

[07:19] on this object on the apple object that

[07:22] we have created

[07:24] similarly

[07:25] we will

[07:27] set the name

[07:31] for the banana object

[07:44] there's an extra bracket here let's move

[07:46] it

[07:51] now moving forward let us type the code

[07:56] to display

[07:59] what we have added into the objects

[08:04] for this can you guess which method will

[08:07] be using

[08:09] yes the get name method

[08:12] will be used to display

[08:15] the name saved onto the object using the

[08:17] set name method

[08:40] now that our code is complete

[08:43] let us run and check

[08:46] if it's working correctly

[08:50] let me go back

[08:52] and refresh

[08:55] now here we have our object.php file

[09:00] yes the code runs perfectly the fruit

[09:02] program and it is displaying apple and

[09:04] banana from the two objects that we

[09:06] created i hope now you have clearly

[09:09] understood the concept

[09:11] moving on to the next one let's talk

[09:13] about the member variable and member

[09:15] function

[09:16] a member variable is defined within a

[09:18] class

[09:20] the data can be accessed by the member

[09:22] functions alone

[09:23] now once the object is built these

[09:25] variables are called attributes of the

[09:27] object whereas member function is

[09:30] defined within a class and is used to

[09:32] access object data

[09:34] if getting your learning started is half

[09:36] the battle what if you could do that for

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[09:41] the link in the description to know more

[09:44] so next comes constructor

[09:47] so it allows an individual to alert an

[09:50] object's properties

[09:52] while the object creation

[09:54] while a destructor is a function that is

[09:56] called when the object stops working

[09:59] we will have a look at the constructor

[10:02] program

[10:03] so constructor allows an individual to

[10:05] alert an object's properties while the

[10:08] object creation

[10:09] now suppose you build a program using

[10:11] constructor function

[10:13] php will automatically call the

[10:15] construct function while creating an

[10:17] object from a class also remember that

[10:20] when you write the construct function

[10:22] always prefix it with two underscores

[10:26] now let's have a look at the example

[10:28] where we will be using a constructor

[10:30] function with calling the set name

[10:31] method

[10:33] now this set name function is often used

[10:36] when you assign a value to the name

[10:37] attribute

[10:40] now let's open the code editor and

[10:43] create a constructor file

[10:54] [Music]

[11:11] we'll again create the two properties

[11:14] named

[11:16] name

[11:19] and color

[11:22] now we will create a constructor

[11:25] with two underscores

[11:27] and a construct keyword

[11:30] and i'll give the two properties as

[11:33] attributes to the constructor

[11:39] now in this

[11:41] program we'll be using the constructor

[11:43] function

[11:46] as the set

[11:48] method

[11:49] to set the names

[11:52] and color of a fruit by default

[11:56] during the object creation itself

[12:08] we still need to create the get

[12:11] functions

[12:29] so

[12:41] now let's create an object to invoke the

[12:44] constructor

[12:54] now since the constructor has attributes

[12:56] we will have to give the values for the

[12:59] attributes as well

[13:01] so the fruit would be

[13:03] strawberry

[13:06] and

[13:07] color

[13:08] would be pink

[13:11] so this creates a new object and it

[13:14] gives

[13:16] the values to the constructor

[13:33] uh

[13:58] in the php script

[14:01] and

[14:02] our html code as well

[14:09] let us save the code and check if it's

[14:11] working

[14:14] let's go back

[14:16] refresh

[14:17] now constructor file is visible let's

[14:20] click on it and yes

[14:22] so

[14:23] when the object strawberry is created

[14:26] the attributes we have given to the

[14:28] constructor strawberry and the color

[14:31] pink were already

[14:33] assigned to it

[14:35] and it is displayed in the browser

[14:36] itself

[14:38] now that the constructor program is done

[14:40] next let's see an example of how a

[14:42] destructor works

[14:44] let's open the code editor

[14:47] create another file

[14:49] destructor.php

[14:52] now the destructor code will be very

[14:54] similar to the constructor one so we

[14:56] will copy the code

[14:57] into the destructor file and make some

[14:59] changes

[15:01] so

[15:02] let us remove this we don't need it

[15:07] and write our destructor function

[15:11] so destructive function is written

[15:13] similarly

[15:14] how constructor function is written

[15:17] so it starts with two underscores and a

[15:20] destruct keyword

[15:23] it does not have an attribute

[15:28] now why did we delete the get functions

[15:31] is because

[15:32] we will be using the destructor

[15:35] for it

[16:15] also we won't be needing this

[16:20] just the object creation is sufficient

[16:26] now let's save our program and

[16:30] do the drill again

[16:34] open the browser

[16:39] here a destructor file is visible

[16:42] and it shows the fruit strawberry and

[16:44] the color is pink so when the object

[16:47] function is complete

[16:50] and the program ends the destructor

[16:52] function is called which displays the

[16:55] strawberry and the color pink

[16:59] now

[17:00] comes inheritance so it derives new

[17:02] classes or child classes from the parent

[17:05] class

[17:06] however inheritance can have its own

[17:08] properties and methods too

[17:10] so inheritance has two classes

[17:13] first is parent class and the other one

[17:15] is a child class

[17:17] now let's talk about each of them in

[17:18] detail

[17:19] so parent class is otherwise called a

[17:22] base class that is inherited from

[17:24] another class

[17:26] and a child class is a subclass that

[17:28] inherits from another class

[17:31] a child class can have subclasses and

[17:34] derived classes

[17:35] now let's have a look at the inheritance

[17:37] program

[17:38] so the child class is derived from all

[17:41] the properties and methods from the

[17:43] subclass

[17:45] in addition it can have its own

[17:47] properties and methods too

[17:49] so an inherited class is defined by

[17:52] using the extends keyword

[17:54] let's look at an example

[17:57] open the code editor so i have taken the

[17:59] liberty to create the inheritance.php

[18:02] file

[18:03] and write some of the code that we have

[18:05] already written so i'll be writing only

[18:07] the code that is necessary for the

[18:09] inheritance part

[18:14] now also remember when you derive a

[18:17] child class from a parent class only the

[18:19] public methods are derived into the

[18:22] child class

[18:23] so we will be creating the methods as

[18:26] public

[18:27] in order them to be

[18:29] inherited

[19:17] made this function public

[19:27] let's

[19:28] end this class

[19:30] and create another class in order

[19:34] to inherit this class

[19:38] so we will name

[19:40] another class as

[19:43] cherry

[19:45] extends

[19:47] fruit

[19:52] and we'll create another function for

[19:56] cherry so this function is exclusive to

[19:58] cherry

[20:28] so we have given a message through this

[20:30] method

[20:32] now

[20:34] let's create an object

[20:37] cherry

[20:39] new

[20:40] cherry

[20:42] and

[20:45] give the values for the attributes

[20:47] of

[20:48] this constructor

[21:24] let's save the code

[21:26] and check if it's working

[21:35] well there seems to be an error

[21:38] now let's try to resolve it

[21:45] okay got it so we

[21:47] created the object

[21:51] within

[21:52] the cherry class so it got localized

[21:57] what we need to do is put that code

[21:59] outside of the cherry class

[22:02] and it should work fine now

[22:08] yes so is cherry a fruit or a berry a

[22:12] cherry is a fruit and the color of the

[22:13] fruit is red

[22:15] and now we will talk about the last

[22:17] concept that is polymorphism so

[22:20] polymorphism has many forms

[22:23] the same function is utilized for

[22:24] different purposes

[22:26] it has a class with a variety of

[22:28] functions simultaneously sharing a

[22:30] common interface

[22:33] so inherited methods are overridden by

[22:36] redefining the methods in the derived

[22:38] class now let me write the code to make

[22:42] it clear

[22:44] so already created the polymorphism php

[22:47] file

[22:48] i have copied the inheritance code

[22:51] into the polymorphism part

[22:54] and then now we'll make the changes into

[22:57] the derived class that is cherry

[23:03] so let's create a property named

[23:07] wait

[23:11] now to

[23:12] override the constructor and the intro

[23:16] function

[23:17] from the fruit class we will have to

[23:19] create the same functions

[23:21] in the derived class also

[23:35] now this function construct has got one

[23:39] extra attribute in comparison to this

[23:41] function construct

[23:50] okay

[24:24] let's create the intro function too

[25:30] now a code is ready

[25:32] let us create another object

[25:36] to invoke

[25:38] the functions

[26:10] now did you notice what we did here

[26:13] so

[26:13] when we created the object cherry for

[26:16] for the cherry class we gave three

[26:19] attribute values instead of two

[26:22] in order to invoke this construct

[26:24] function

[26:27] not this

[26:39] let us run it and check

[26:50] so it runs perfectly it displays the

[26:52] fruit the color and the weight

[26:56] now we have reached the end part of the

[26:58] video on the object-oriented programming

[27:00] in php

[27:02] i hope it was informative and

[27:04] interesting and if you have any queries

[27:06] about the topics covered in this video

[27:08] please ask away in the comment section

[27:10] below our experts are 24 7 ready to

[27:13] solve your queries thanks for watching

[27:16] stay safe and keep learning

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