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Next, we're going to look at members of classes, and there are multiple different types of members.

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The simplest one are member variables, so no variable, let's call them properties.

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Alternatively, so you can either call them a verbal or properties, what would be an example property

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for a person or a useful property?

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Well, there are plenty, but for example, age would be a very useful one.

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So let's say we have the age.

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And it can be, no, okay.

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So why would I create a variable called age that can be null for a person?

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Well, the thing is that let's say we have the data of a bunch of people, so a bunch of users in our

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database.

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And for most of them, we don't have the age.

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For some of them, we do have the age, but we have all of them the first name and the last name.

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So we want our program to run no matter if we have the age or not, it should still work.

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But if we have the age, then we maybe want to do something special.

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We either want to display it on the app or on the website, or we could even go so far and to say Happy

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Birthday or whatever.

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If we don't have just the age, but the actual birth date, for example.

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All right.

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So this is an example of a member variable, and we can have more of those.

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So let's say I have a hobby here as well, which I'm going to define as and watch Netflix.

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So this is going to be the default value.

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And this is an example for the member variables.

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Now let's have a look at member functions.

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So there is something called member functions.

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You can also call them methods.

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All right.

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And a member function is a function within a class as a member, variable is a variable within a class.

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OK, so the member function that I'm going to create is just going to be a very simple one, which is

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going to state the hobby of someone.

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OK?

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So the only thing that it should say is front line.

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My hobby is.

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And then the hobby.

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All right.

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So another cool thing is we can go ahead and do the following.

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So let's say then is that a state hobby?

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So let's see what will be printed onto our console.

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So there we are, initialized in new person object first names and his last name by Newton, my hobby

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is Netflix or is watch Netflix.

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OK, so that is cool.

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But now the problem is the hobby is the same for everyone.

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So how can I change it?

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Well, you can change it the following way.

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You can go ahead and say Dennis thought hobby should be something different, such as skateboard.

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All right, so maybe Dennis likes to skateboard.

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And then if you run this code again, we will see that now my hobby is skateboarding.

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Maybe we should add something like to skateboard in here or something like that, but yeah, overall

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the logic is the same.

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Okay, so what we now can do is and that is pretty cool.

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We can have an individual hobby for every single person because every single person already has something

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that is unique to them or individual to them.

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Unique is a little difficult to say because probably there are other John Doe's in the world.

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But what we can say now is that the hobby of John should be something else, such as play video games.

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All right, so John Doe likes to play video games, and now we can state his hobbies here as well.

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So I'm just going to say John thought state hobbies.

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Now, if we run this, then we'll see that John's hobby is to play video games.

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So this is just an example for why object orientation is so powerful or object oriented programming,

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because we can now create blueprints, our classes for our own data types or objects that we can then

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go ahead and use.

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So I create an object here, which is a variable.

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So a variable is an object if it is of a type, which is a class.

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OK, so in Scotland, pretty much everything is an object.

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Even the basic and generic data types, such as ins and strengths are classes sold to say.

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And you can see that when you entered into keywords, you can see that this is a sea, which means that

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this is a class game.

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So we create our own data types here.

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We can change their properties and we can use their methods, which we can define ourselves as well,

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so we can go ahead and create as many methods as we want.

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In the last video, we looked at scope.

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Why would we do that?

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Because we're not using scope here, and I said that we needed scope in here.

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Well, because we are using first name here, right?

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So in our in it, in our initial laser block, we use this variable name, first name and where does

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it come from, where it comes from, our constructor here.

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So this is our primary constructor.

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And now in order to understand that, we need to create another constructor.

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So what I'm going to do is I'm going to create a constructor here, and a constructor is also a member,

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member constructor.

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To be more precise.

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This is a secondary constructor.

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All right.

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So what I can do is I can now say what kind of variables I would like to have when somebody is creating

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an object of type person who did that already here.

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But I can have a secondary constructor where I say I want also to have the H.

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So whenever somebody creates an object of person, they can also pass in the H and we will then use

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it.

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All right, so I can go ahead and say, OK, give me the first name.

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Give me the last name.

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But also give me the edge, which will be of Typekit.

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Now, what we need to do here is we also need to add a column and then this first name, last name because

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we are using the two.

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OK, so I'm just going to put that in the second line here.

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So this is our new constructor that we created our secondary constructor and now we can go ahead and

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say that our h that we have, there should be the h that is passed to us.

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So I'm using this, this keyboard here twice.

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So you might wonder what is does this?

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Well, this this is a little easier to understand.

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So what I'm saying is that the H that is given to the constructor when the object is created should

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be assigned to the edge of this class, which means that it's going to be this one here.

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This H that we created here at the top.

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So to the member variable or to the property, it should be assigned to the property.

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So that's what I'm saying with this.

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OK, now this this here, it says that the first name and last name that we're using here in our secondary

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constructor should be the ones coming from our primary constructor.

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So there should be the first name that is passed here, John.

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And the second name that is passed here, which is the last name.

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So what we can do now is we can go ahead and give some more information.

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So let's say I create a person which is called Dennis, and I also pass to H.

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So I don't only pass the first name and last name, but I also pass in the H.

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So Dennis will now have an h.

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So if I go ahead and say Dennis, that H is equal to Th2, then the initial h that was set will be overwritten.

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So now if I want to print it, I can just do that.

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Print Dennis Start H.

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And maybe I should add a little more information.

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Dennis is then is that age old?

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And here we need to use brackets.

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Years old.

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So now let's run this again.

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And we are so we can see initialized the new person last name, then Newtown, and then Dennis is 32

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years old.

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And yeah, as a hobby of skateboarding.

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All right, so now the cool thing is we can provide an own print and statement when this other initialize

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I is called.

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So here I'm just going to say initialize the new person object with first name, last name and then.

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And H.

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So let's run this again.

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So now add initialized the.

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First constructor.

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So our primary constructor here, which was run by this initial as a block, as we saw earlier.

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And then it render constructor, which is our secondary constructor.

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And added this and here.

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All right.

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So now another thing about the first name, so let's say I want to extend my state hobby here.

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I want to say whose hobby it is.

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So he just says my hobby, but we didn't or we don't know who my is because of course, here we know

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that it's John, but that's because we programmed it.

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But what if we only see the output so we will never know which person's hobby it is?

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All right.

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So in order to change that, I want to go ahead and to finally come back to where I started with this

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whole thing.

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I want to use the first name here.

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And I want to use it like this.

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The problem is, this doesn't work, why does it not work?

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Well, because the first name isn't the variable that is invisible because it's only visible within

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this primary constructor here.

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And it's also visible within our secondary constructor now that we have thunder.

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So what I did with the H is what I can now do with the first name as well.

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So please go ahead and try it.

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Create a new variable.

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You can call it a little different just to avoid confusion and then use it in your state hobby as well.

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All right.

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So I hope you tried it, and maybe the exercise wasn't 100 percent clear.

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I'm sorry for that.

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But the idea is that we're creating a new first name here, which should be of type string, and it

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couldn't be now, so it can be empty.

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And then we go ahead and in our in it, so in our initialize up, we assign to this first name, we

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assign the first name.

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So we do.

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What we did here, so we take this first name and we store it within the member variable, so now we

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can go ahead and use it in our state hobby.

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So here I can go ahead and first name.

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And I'm going to use a.

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Backslash.

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Apostrophe here.

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And s just to say, for example, Dennis's hobby is Holly.

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So let's run this again.

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And now we see Venice's hobby is to skateboard, Jones hobby is play video games.

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So now we have a lot more knowledge about which object we have manipulated and which object does what.

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All right.

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So I think this is enough for this video, enough of different concepts that we're using.

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I told you that the class can have multiple members and the ones that we saw are not the only ones.

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Classes can contain multiple members here, constructors and initialize of blocks, functions, properties

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nested in the classes and object declarations.

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And we're going to see what those different things are later on.

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But for now, just know that there are multiple members that a class can have.