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‫Welcome back.

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‫In this video, I would like to talk about access modifiers which allow you to grant and prevent access.

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‫And in order to understand access modifiers a little better and the reasoning behind them, we need

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‫to look into certain concepts.

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‫So first of all.

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‫Marking fields and methods with access modifiers is part of the object oriented programming and increases

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‫the safeness of your code and are an important part of encapsulation, which is a part of OP.

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‫We will look into what this means a little more so in object oriented programming.

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‫Languages such as C sharp encapsulation is used to refer to one of two related but distinct notions,

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‫and sometimes to the combination thereof.

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‫So a language mechanism for restricting direct access to some of the objects components such as their

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‫variables and their methods, a language construct that facilitates the bundling of data with methods

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‫or other functions operating on that data.

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‫So for example, we can use setters and getters in order to make our whole program safer.

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‫We will look into that a lot more once we go into properties which will allow us to do loads of the

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‫stuff that we're going to look at in this video.

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‫All right.

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‫So first of all, the access modifier, private, private is only accessible inside a class or construct.

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‫So if you create a private variable or a private method, it is only available within the same class

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‫or structure.

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‫So you cannot use it anywhere else.

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‫So let's look at an example here we have class one with private int h and private void walk, which

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‫is a method.

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‫In this case, the method doesn't do anything, but there could be some code in there.

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‫And now we have a second class, class two in which we create an object of class one, which is called

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‫first class.

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‫And then we want to access the edge of that first class object, which is 18.

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‫But unfortunately we cannot do that because it's private.

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‫So we cannot access this variable the same thing for the walk method.

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‫We cannot access it because it's set as private.

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‫So they are not accessible from another class.

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‫They can only be used within class one.

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‫Then we have the public access modifier which makes it accessible from everywhere in your project.

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‫So when you use public for a variable or a method, it can be used in every single class that you have

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‫within your whole project.

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‫It's not limited at all.

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‫Here.

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‫An example again public int h and public void.

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‫Walk the variable and method here and in class two we try to access them and in this case it works totally

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‫fine.

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‫So they are accessible from anywhere.

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‫So we can of course use them in class two.

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‫Then there is the access modifier called protected and that allows us to make something accessible from

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‫the class and all classes that derive from it.

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‫That's why it's important that you understand OP in order to or object oriented programming, in order

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‫to really make use of that.

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‫So we have this protected int h 18 and protected void walk.

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‫So in this case we have a class two which inherits from class one and you can see it can access H now

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‫it can access H directly.

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‫We don't even have to create an object of our class one.

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‫So that allows us to access the variable directly as if it was public.

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‫So protect it is like public but only for the same class and classes that inherit from it.

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‫The same goes for walk, so the walk method can be used in here easily as well and directly as well.

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‫And then we have the access modifier.

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‫Internal and internal variables and methods are only accessible from its assembly, so from the same

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‫namespace or the same project.

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‫So if you have a namespace.

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‫When would you have multiple classes then?

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‫All of the classes can access internal variables and internal methods.

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‫So how do we use access modifiers correctly?

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‫So as a rule of thumb, whenever you declare a new class member or method, I'd recommend to you initially

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‫going with the most restrictive access modifier that will allow your program to work and then you can

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‫relax it when necessary.

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‫So make everything as private as possible.

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‫And when your variables or methods should be used somewhere else, then you of course have to ease it

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‫a little bit.

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‫So then you could use, for example, internal, protected or even public.

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‫So why should you use access modifiers?

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‫Well, they give you full control over your methods and variables.

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‫A very basic example would be H.

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‫So let's say you want to be able to set the H, so if you would make H public, then anyone could change

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‫the age variable and every class could change to h variable, even if the value doesn't make sense at

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‫all.

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‫So somebody could enter an H of -20 or -25 or something like that.

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‫But if you control the variable via private, so if you only have setters and getters or use properties

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‫as we will do later on, then you can make sure that this age variable, if it's set with a value,

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‫that doesn't make sense.

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‫So for example, a negative value that is just multiplied with minus one, or if it's a value, let's

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‫say that is over 150 or 130 or something like that, then you would set something like zero or set something

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‫like incorrect name, or you could throw an error, you could show incorrect value.

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‫Enter, please enter something else.

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‫Or you could just start a routine which for example, informs the right software or the right employee

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‫that needs to take care of incorrect values or whatever.

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‫So this is what you, as an example, can do, but there are plenty of other examples which you can

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‫do, and we will look into access modifiers a lot more in the next videos.

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‫So I'd say let's check out some more concepts around X modifiers, encapsulation and so forth.