OOP for Beginners: Build a Bank Account App with Classes & Objects

hi guys and welcome to my channel in this video you are going to learn objectoriented programming through

practical examples so that you can apply your knowledge and build real applications I will create a series of

videos where I will teach you all of the oop principles through practical examples and this video is the first

video of that Series so in this video you are going to learn what is oop what are classes objects and how to use them

and together we are going to build an interesting application so before we start writing any code you first need to

understand what is oop and why it is important oop stands for objectoriented programming and it is approach in

programming that helps us to represent real objects from Real World in our programs and that way it helps us to

solve real problems and create modern useful applications that you and me use every day because as I said with oop we

can represent real objects from real world together with their properties and their behaviors and we can translate

that into our applications in this video we are going to build an application with C but oop principles and the logic

that you learn are the same in all oop languages which means that principles that you learn in this video can be

applied across all oop languages such as C++ C Java JavaScript python PHP Ruby Swift and many many more languages so

now that you know that oop is approach in programming that helps us to represent objects from Real World in our

applications together with their properties and their behaviors now the question is what are the most important

Concepts in oop two most important Concepts in oop are classes and objects and they help us to represent entities

from Real World in our applications together with their properties and their behaviors a class serves as a blueprint

as a model and a class tells us which properties and which behaviors that entity has and then an object is a

concrete instance of that class let me give you an example of what is class and what is an object a class can be for

example a person each person has certain properties each person needs to have name age birth country weight and so on

so that is a class it's a blueprint an object is a concrete instance of that class for example an object of class

person can be me with all of my properties my name is salinaa my age is 29 my birth country is Bosnia and so on

another object of class person can be you with your name your age your birth country and so on and please let me know

in the comment section what are your properties what is your name age and where are you watching this video from

I'm very interested to know the people who are watching my videos so once more a class serves as a blueprint or a model

and it describes what kind of properties and behaviors objects need to have and then objects are concrete instances of

that class now let me show you how this works on the application that we are going to build today here I have already

finished application that we will later build together and this application is used in order to manage bank accounts in

this grid we already have two bank accounts one is mine this is owner name account number and then this is the

balance of my bank account and then another bank account is from Elon Musk this is his account number and then his

balance and then also I have the option to create a new bank account so let's say Bill Gates and I say create account

so another bank account will be added this is the owner this is the account number and then balance will initially

be zero because we have just created this account and besides that we also have these two buttons option to deposit

money and to withdraw money from bank account so if I select for example my bank account and I say 100 and I click

on deposit that money will be deposited to my balance also if I select another bank account let's say Elon Musk and I

say 200 and I click on withdraw that money will be withdrawn from his bank account so this is an application that

is very easy to use it is very straightforward it is not especially beautiful because I have not added any

colors I have not styled it in any way but it is very functional and in this video we will learn how to build this

application hey there if your goal is to learn programming and start a successful career build interesting and useful

applications and if you enjoy learning from my you videos then you should definitely enroll in my practical

programming course I will take you from beginner to expert in just a few months and I will give you all of the support

and help that you need to achieve your goals in the course you will work on realistic projects you will get access

to a large community of successful developers and everything that you need to learn will be on one place you just

need to follow the plan that I have created for you and those of you who finish the course successfully will get

a special certificate that is going to open a lot of job opportunities for you in the description you can find a coupon

code to save some money and if you're not sure if this course is for you or not we have 7-Day money back guarantee

which means that if you don't like it for any reason you will get all of your money back no questions asked so now

instead of coming up with excuses use this opportunity to finally learn programming and transform your life

because you really have nothing to lose and a lot to gain so first let's explain what is in the background of this

application and how we can build it so in the background we have one class called bank account and that class says

that each bank account needs to have an owner account number and balance those are the properties of each bank account

and then also it needs to have certain behaviors so we need to be able to create a bank account we need to be able

to deposit money and withdraw money from bank account so that is an example of a class in our program and as we said

class serves as a blueprint and it defines what kind of properties and behaviors objects need to have in our

case class defines that each object needs to have owner unique account number and balance those are the

properties and then behaviors that bank accounts need to have is the ability to withdraw money deposit money and to

create new new bank account and then objects of our class are these three instances here they are concrete

examples of bank account class so this is the application that we are going to build together and in order to build

this application together with me you will need to install Visual Studio 2022 or newer Community version is completely

free and I will leave a link in the description that you can use to download it and also you will need to install Net

Framework my recommendation is that you install NET Framework 8.0 because that is the newest version as of filming this

video you can also install some newer version depending on when you are watching the video and also I will leave

a link to download and install it in the description so once you install those two let's open our visual studio and

let's build this application so here is my visual studio let's click on create new project okay and here we are going

to create C Windows forms application make sure that you select C and not some other language

so C Windows forms app select that and click on next and here we will give the name to our application let's say bank

account app and then click on next again and here you will select your framework for me that is

8.0 and then click on create so here is our project and initially we get this form called form one and that is this

empty form here and if I start my application that form will be started but as you can see it is currently

completely empty because we still have not added anything to our form so now let's do that let's add our controls

let's add our grid buttons and so on I will show you this already finished application again so that you can take a

screenshot if you want because now we want to build our application so that it looks the same same as this already

finished application we want to add the same controls and then we will write the code and implement the same behavior so

I will have this already finished application on the other screen and now we will build our application to look

the same and the reason why I picked Windows forms framework is because it gives us an easy way to create all of

those controls that you could see on our form so that we don't have to spend a lot of time doing it manually and in

instead we can focus on writing the code so now let's design our form make sure to open this designer view off your form

and then open toolbox go to view toolbox and here you will get a list of all of the controls that you can simply drag

and drop onto your form so let's first find a label control you can simply drag and drop it onto the form as I said and

here is our label now you probably can not see this text so let me very quickly increase the font right click on the

form go to properties and here you will find font property so simply click on three these three dots and here I will

increase the font to 16 I believe that will be enough okay so let's just shrink this form a little bit like this okay so

now this is our label and what I want to do is I want to change the text that is displayed in this label so simply right

click click on the label go to properties and here you will find text properties so what I want this label to

say is this text so I want it to say owner and when I press enter as you can see the text will be changed so now

let's copy this label and paste it because I want to add another label but the text of this label will be

amount like this okay so those are two labels that we need now let's add other controls let's also add a text box where

we can enter owner's name and then a numerical field where we can enter the amount so let's go back to our toolbox

and here I will find control which is called text box and I will simply drag and drop it on my form and let's just

make it a little bit bigger so this is our text box this is where we will enter owner's name and then let's also add

another control it is called numeric app up down and that is the control where we can enter numbers and I will put it here

these are controls that we will use when we want to enter owner's name and then the amount that we want to withdraw or

deposit to our bank account so that means that we will need to access these two controls from our code and for that

we use their name so if I click on this control here you will notice that it already has a default name it is textbox

one but what I prefer to do is to give meaningful name to all of my controls because that way I can remember it

easily and I will understand my code better so I will call this control owner txt okay that is much better than

textbox one and then I will also change the name of this control here again right click on it go to properties and

here you will find name property and I will call it amount num so amount numerical okay now let's also add our

grid that will serve as a table where we can show all of our bank accounts so let's go back to toolbox and here I will

find control called grid it is called Data grid View and I will simply drag and drop it to my form like this and

let's just make it a little bit bigger like this okay so inside this grid we will show all of our bank accounts so

let's also change the name of this grid control right click on it go to properties and find name property where

is it it is here so instead of data grid view one I will call it bank accounts grid like this and the only thing that

remains is to add three more buttons so let's go back to toolbox here I will find button control and I will drag and

drop it here let's just make it a little a little bit bigger so this is going to be our first button I will copy it and

paste it here because we need two buttons here okay and I also need another button

which I will copy and paste here and we will also need to access these buttons in our code in order to describe their

behavior so I will also change their names so this button here will be called create account BTN

like this and please notice that when I change the name the text of the button will not be changed because we use the

name in the background to access this control and then text property is what the user sees so if you want to change

this text here this button Tre then you need to change the text property so let's find the text property it is here

and here I will say create account and now the text of the button will be changed and now let's do the

same for these two remaining buttons so this button here its text will be deposit that is what the user will see

and then the name that we will use is going to be deposit BTN like this and then this button here

its name is going to be withdraw BTN like this and then the text is going to be simply with

withdraw like this so that is all that you need to do in order to build the user interface of this application and I

can even start this app and this is what we get here we can enter letters here we can enter numbers and then we can click

on these buttons but currently our application doesn't do anything because we still have not written any code so

now let's focus on writing the code let's see how we can create our first class because here in this grid we are

going to show all of our bank accounts so now let's see how we can create a class that will describe how each bank

account should look like so here on your project on your bank accounts app project right click on it and click on

add new item and what we want to add is a class and here you will name your class I will call it bank account

like this and then simply click on ADD so this here is our class it is called bank account and all of the

properties and behaviors that our class has we will write them inside these curly brackets here so as we said bank

account class will have three properties it will have owner property that is the name of the owner that you enter in the

text box on our form and then it will have bank account number which is unique identifier of each bank account and then

third property will be balance so let's now add those three properties to our class so let's say public string owner

and then here I will put get and set inside these curly brackets owner is the first property of our class and it is of

type string because here I'm entering first name and last name of my user and that is in string format and then this

part here this public access modifier and then this get and set inside curly brackets please write them the same way

I'm doing now and then later in this course we are going to explain what is the purpose of this and what is the

purpose of this for now let's just focus on things that are more important now let's also add account number property

so I will simply copy and paste this property here and then change its name let's call it account number like this

it should also have this public and get and set don't change that for now and then it can be of type string but then

you will have to take care yourself to create a unique account number and if you don't want to do that what you can

do is you can use a different type here and that type is called guid and what guid is going to do is it is going to

give you globally unique identifier every time that you request it so you can simply say hey please give me a new

GID and then it will give you a unique ID that you can use as your account number so it is much better to use good

here instead of string and then let's add third property and that is going to be

balance like this and balance is going to be of type decimal because here we want to enter how much money our bank

account has and then also this part here and this part here they stay the same so this is how you create a class it is

called bank account and all of the properties and all of the behaviors of that class you need to write inside

these curly brackets and here we have just added three properties for our class and those are owner which is of

type string and then account number which is of type guid so globally unique identifier and then balance which is of

type decimal so with this we have created our class and there is just one more thing that I want to change here

and that is this internal access modifier so here I also want to say public and as I said later we are going

to explain in detail what these access modifiers mean for now you can just understand that this is a way to prevent

or allow access to our class and right now everything is public which means that we can access everything and then

later in this course we are going to learn different types of access modifiers and how how to use them for

now everything is just going to be public okay so this is our class and now let's create objects of this class now

we want to show objects of this class inside this grid here so we will also create those objects in the code behind

of this form something that I didn't tell you before is that each form consists of three parts and this here

that you can see that is the user interface part part of your form that is the first part the second part of your

form is code behind which means the place where we write the code now how can you find that code behind it's

actually very easy you just open your form and then you press F7 and that will take you to the code behind of your form

and another way if this shortcut doesn't work is to Simply write click on your form and then click on view code and

that will take you to the same place so this here is the place where we write the code and as you can see our form

itself is also a class and you will notice here that it is partial class and what this means is that it consists of

multiple Parts as I already explained this here is one part of our form and then this here is another part of our

form and because of that our form is partial class and then third part of our form is this form 1. designer. Cs and

this file here is automatically generated which means that we should not write any code inside it and we should

not touch it so code behind is the place where we are going to write the code for our form now please take a look at this

method here this is a special type of method called Constructor and Constructor is the first method that

will be invoked when a class is created so when we start our application this is the form that will be started

and in order to construct this form what our operating system will do is it will invoke its Constructor so this method

here will be executed when our form starts which means that inside this method inside this Constructor we can

put any code that we would like to execute when our form starts so what I would like to do is I would like to

create a few objects of bank account class and then show them inside my grid now there are different ways and

different approaches to do this but for now let's go with the easiest approach so we will write the code here inside

the Constructor of form one let's see how we can create an object of bank account class so you simply say bank

account so the name of your class and then you give the name to your object my object will be called called bank

account with lowercase letters and then I will simply say please create new bank account like this so this is very

similar to creating normal regular variables you first specify the type of your variable and then you give the name

to your variable and then in case of objects you also need to say that you want to create a new object of that type

and for now it is going to be empty which means that we have not assigned any values to the properties of this

object and for that reason these parentheses are empty so now let's assign the values to the properties of

this object so how can we access those properties well you simply say bank account Dot and then here you can see

many many things and among those things are the properties that we have created for example here is our owner property

so you say Bank account. owner and now you can set owner property so who will be the owner of my bank account let's

say Saina nurak that is my name okay so this is the owner of bank account and then let's say bank account dot account

number and here I will say guid do newu like this and it is going to assign find a new unique identifier to this

property which means that account number will be unique okay and then third property is bank

account. balance and here let's say for example 250 like this so with this we have

created an object of class bank account once more you first specify the name of the class and then the name of the

object and then you say that you want to create a new object which will be empty for now and then you assign the values

for the properties of that object so Bank account. owner will be Sala norak and then bank account. account number

will be new unique identifier and then bank account balance will be 250 now let's create a few more objects

of bank account class and then we will show them inside our grid so I will copy this entire code here and then paste it

and here I want to create object called bank account 2 so bank account 2. owner will be let's say Elon Musk and then

bank account to. account number will be again give me new unique identifier and then bank account 2. balance will be for

example 999 that is how much money Elon Musk has okay so this here is is second object

and then let's create one more so I will copy and paste the code and here I will change the name of the object let's call

it bank account 3 again I'm creating an empty object and then I will say bank account 3. owner will be let's say Bill

Gates and then bank account 3. account number will be new good and bank account 3. balance will be let's say

150 okay so with this we have easily created three objects of bank account class and now let's see how we can use

these objects in practice so for example let's show them inside this grid here now in order to show data inside our

grid we need to put that data inside a list and then we can simply set that list as the data source for this grid so

let's go back to the code behind press F7 and here I will create create a list of bank accounts I will call them bank

accounts and for now it is going to be new list which is empty and now what I will do is I will say Bank

accounts. add so what I will do is I will add this first bank account and then also I will add bank account two

and then bank account three like this so now that I have inside this list all of my bank accounts accounts what I can do

is I can set this list as the data source for this grid here and in order to do that and in order to work with

this Grid in our code we need to know what is its name so let's check one more time what was the name that we gave to

this grid so simply right click on the grid go to properties and find name property it should be here somewhere so

the name is bank accounts grid Okay so so now let's close this properties window and let's press F7 to go to the

code behind and here I will say bank accounts grid. data source so what I want to do

is I want to set data source for my grid and data source will be this list here which means please show this list of

bank accounts inside my grid so now when I start my application we should see these three objects inside our grid so

let's start the application and as you can see here are three objects that we have created now I know that I said that

we will not style this application and that we will focus only on writing the code but there is one thing that bothers

me a lot related to this grid and that is this empty space here so one small thing that I want to change is I want to

tell to The Columns of this grid to fill this entire space so that is one thing that I want to change so let's close our

application and let's go to this design of our form right click on the grid go to properties and here you are going to

find the property which is called let me check it is called Auto siiz columns mode that is the property that you need

and here you need to set it to fill which means that automatically the size of columns will be to fill the entire

grid so now if I start the application you will see that our grid looks much better and there is no more empty space

in our grid so in this video we learned what is object-oriented programming and how we can use it in order to build real

useful applications we also learned what are classes and what are objects and how to use them in practice in our

applications now there are still many many things that we need to add and Implement in our application but let's

do that in the next video because this video is already becoming too long on my YouTube channel you can find an entire

playlist about practical oop so practical objectoriented programming and you can watch all of the videos and

learn everything that you need about objectoriented programming and if you want to learn practical programming in

general so that you can start a career as a software developer and work on real projects in real companies then you

should join my practical programming course because there I will teach you everything that you need to know in the

shortest amount amount of time so that you can get a job as a software developer I will be there to help you in

every step of the way and your job is just to follow the plan that I have created for you so in the description I

will leave a special coupon code that you can use in order to save some money and get a discount and then if you're

not sure if this course is for you or not we have a 7-Day money back guarantee which means that if you're not satisfied

for any reason you can get all of your money back no questions asked from our side so instead of coming up with

excuses use this opportunity to finally learn programming and change your life because you really have nothing to lose

and you have a lot to gain so that would be all for this video if you have any questions you can leave those in the

comment section and please write your questions in the comment section instead of sending them directly to me in

private messages because when I reply to a public comment then all of the other people can also see that answer and they

can benefit from it and also if you enjoyed this video and if it was beneficial for you please give it a big

thumbs up so that I know and I can create more videos like this one so thank you very much for watching and I

will see you in the next video of this series which will be linked here on the screen