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‫Welcome back.

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‫In this video, we're going to check out data, types and variables.

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‫So pretty much the process of storing data in a variable.

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‫Now let's dive right into it.

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‫First of all, variables can be pretty much declared outside of a method, but also inside of a method.

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‫And if we have a variable here in this example, it's an integer variable, so it's a variable of type

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‫int and we have given it the name age and assigned the value 15.

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‫So we declared a variable called age of type int and defined the value of 15.

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‫So we assigned 15 as its value.

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‫So this is a variable of type integer and if we want to use it now, we simply have to use the name

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‫of that variable and it will pretty much output 15 in this case.

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‫So console right line gives us the age and the age was 15.

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‫So whatever value we assign here will also be used in here.

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‫So we pretty much stored the data and now we can call it any time we want.

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‫And we are inside of this main method here, which is the starting point of our program.

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‫And by the way, we are within a class here.

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‫So the class is called lecture and that's the general structure of a C sharp type of code.

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‫So you have a class, then you have the main method, which is the starting point of your program where

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‫everything begins.

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‫All right, now let's have a look at this.

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‫What we can see here is that the variable now has the value of 20, because we started off with 15,

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‫as we did before, but now we assigned a new value to it later on.

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‫And that's very common.

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‫That happens a lot.

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‫And as you can see, we assign a new value of 20.

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‫And now if we print out using this console right line statement, then suddenly we will get the value

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‫of 20 and not the value of 15, which we had before then an example with no value.

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‫So in this case we have an age and we have not assigned a value in this case.

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‫So it pretty much means that the default value will be assigned at the default value is zero.

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‫It's different than in other programming languages there.

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‫The default value will be null, which pretty much means empty, but in this case it's zero.

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‫So if we now use console right line age, the output will be zero.

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‫So what if we declare such a variable within a method?

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‫Then it's a different story because now this variable end h will only be available within that particular

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‫method where it was declared in.

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‫And if we want to use H in another method now, it will not be visible.

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‫So we cannot use it there and it will result in errors.

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‫So that's something that you have to keep in mind.

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‫It's important where you declare your variable if you declare it outside of a method.

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‫So here at the top, just within the class lecture, in this case, it will be usable in multiple different

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‫methods, but in this case it will only be usable in the method main because it's declared in the method

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‫main.

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‫But there are more than just the type.

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‫We have checked out the type now, but there are other data types as well.

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‫Let's talk about the different data types real quick.

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‫So first of all, we have this byte which stands for Signed Byte and we call it X and we assigned a

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‫value of 120.

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‫Now signed byte can consist of values between 128 minus up to 127.

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‫So in total, 256 different values.

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‫And this is a very small amount of data.

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‫It will only store a little bit of data, but that at the same time means that this data type doesn't

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‫need a lot of storage, which is great if you want to write very performant software.

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‫Now there is the short keyword as well, which is another primitive data type.

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‫And in this case it can store whole numbers between -32,767 and 32,767.

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‫Then we have the integer which can store values from -2,147,000,000 and some change up to plus 2,147,000,000

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‫and some change.

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‫So again, only whole numbers.

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‫And as you can see, the numbers get bigger and bigger.

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‫But what if you need a very big number to store?

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‫Well, then you would use long.

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‫And as you can see, long can store a very long number.

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‫And in this case, from -9,000,000,000 billion up to plus 9,000,000,000 billion.

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‫And I'm just using billion billion because I'm not sure what exactly the term for such a huge number

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‫would be.

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‫So if you need big numbers, that's the way to go.

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‫Then it's the question, of course, when to use each of these data types, because we have looked in

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‫short byte, short integer long.

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‫When would you use which one?

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‫Well, pretty much use the smallest data type your value fits in.

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‫So the smaller the data that you want to store, so the smaller the value, the smaller the data type

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‫should be that you're using.

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‫So as byte for very small numbers, short for longer numbers, integer for quite long numbers and long

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‫for super long numbers.

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‫Then what if you want to use floating point values?

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‫Well, there are three data types which you can use for that.

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‫One of them is the float data type.

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‫And in this case, we assign a value of 99.99.

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‫And as you can see, we have to add this F here, which tells C-sharp that we're talking about a float

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‫value.

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‫So if we don't use this F, then it will consider it as a double value and we will receive an error.

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‫So it's important to add the F here and we will look into double in a second as well.

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‫So this allows decimals and range from 1.5 times ten by the power of -45 to 3.4 times ten by the power

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‫of 38, you have a seven digit precision here.

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‫So not super precise, but still good enough for most cases.

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‫Then we have the double.

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‫And the only difference is that here we have a 15 digit precision.

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‫So if you need a higher precision and a higher range, then you would use double.

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‫And as you can see, there is no F here and no D at the end.

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‫This pretty much means that we are using a double here.

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‫On the right hand side we have a double and on the left hand side we declare a double.

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‫So this code works.

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‫If you add an F here now, then you will have the same problem as if you had left out the F when creating

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‫a float.

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‫So you have to be precise here.

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‫If you need even more precision and 28 digit precision, then you would use decimals.

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‫So the data type decimal again in primitive data type, but a lot more precise when to use flow double

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‫or decimal.

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‫Well, the same story.

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‫The smaller the value is, the smaller the data type should be.

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‫So it has also to do with performance.

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‫So if you want to create graphic libraries or if you want to write something that has high demands for

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‫processing power, for example, in video games, then you would use float.

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‫This is also used for physics in video games, so then Float is good enough in most real world examples.

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‫Then you would use double except for money calculations and that's where you would use decimal.

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‫So it's mostly used in financial applications where you need the highest level of accuracy.

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‫Now there are other data types as well, primitive ones, and there is this boolean which is similar

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‫to a switch which can only have two values.

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‫So it can either be true or it can be false.

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‫Nothing else.

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‫Only those two.

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‫Then we have the chart or character data type and it will only contain one single letter.

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‫And in order to assign something, you need to use single quotations here.

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‫So single quote start single quote ends and allows a single character literal or unicode.

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‫So here you can store any type of Unicode in here.

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‫And then if you need a longer text consisting of multiple different characters, then you would use

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‫a string.

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‫And you can see here we are using the double code.

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‫So this is pretty much used for text and allows multiple letters and unicode in here.

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‫Now let's start coding and dive right into it.

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‫Oh, and don't forget to rate this course, please.