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‫Welcome to the introduction to Loops and the next chapter.

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‫We are going to cover the different loop types and you're going to learn how to use them in practice.

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‫But first of all, let's have a look at theory and we're going to start off with the different loop

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‫types and the advantages.

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‫So let's check the advantages first.

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‫What are the advantages of loops?

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‫Well, first of all, they save time.

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‫So you don't have to create loads of code, but you can often simplify it and put it into a loop and

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‫they can help you to save time.

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‫Then they are quick and easy repetition module, so they allow you to repeat your code easily multiple

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‫times based on conditions that you set up.

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‫So if you say, okay, I want to run this code ten times, you can simply do that with a loop.

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‫They allow you to work with huge amounts of data so you don't have to check the data manually, but

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‫you can do that with a loop as well.

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‫So that's a huge advantage and we will see when it comes in handy, then it allows you to loop through

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‫a race and that's something that doesn't add too much value yet because we haven't covered the race

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‫yet, but we will do so in one of the following chapters.

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‫So no worries.

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‫We'll get there and then you'll see what the advantages of loops are when we work with the race.

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‫So next let's look at the loop types and there are multiple types.

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‫First of all, the for loop, then there is the while loop which checks and then it goes.

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‫Then there is the do while loop which does first and then it checks and then we have the for each loop

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‫which runs through an array or a list.

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‫And that's what I'm going to show you as soon as we get to your race and lists.

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‫So first of all, the for loop, the for loop has a start value in brackets, then separated by a semicolon,

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‫the condition and the increment again separated.

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‫And then in curly brackets you have the code body.

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‫So that's code that should be repeated.

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‫How often it should be repeated is based on the start value and the condition and of course the increment.

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‫So whatever you set up in those three lines will determine how many times this for loop will be run.

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‫And that's perfectly great for counters.

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‫So for loops are amazing in order to run counters.

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‫Next the while loop you start off with the counter variable.

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‫You set it, for example, to zero.

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‫It could be a different number.

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‫Then you have the while keyword and in brackets you have the condition.

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‫So for example, as long as the count variable is lower than ten, please go ahead and run that while

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‫loop.

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‫Then you have the code that should be executed once the condition is met and it will be repeated as

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‫often as long as the condition is met.

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‫One very important aspect here is to have this counter variable increment.

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‫So you need to increment the counter variable within the while loop.

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‫Otherwise you get an an infinite loop and that's something that you don't want because that will crash

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‫your program.

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‫So that's the general structure of a while loop you can use while loops, not only with integers or

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‫numbers, you can also use them with booleans so you could check if something is true.

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‫So for example, you could check what did the user enter?

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‫As long as the user didn't enter zero, for example, you're just going to add the numbers that he enters.

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‫So that's something that you could check here.

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‫So while a specific condition is not true, so the user didn't enter zero, so it means the bool is

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‫false.

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‫Please go ahead and run the code and it executes the code as long as the condition is met.

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‫And that means that it doesn't only have to be as long as this counter variable, for example, is,

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‫but also based on booleans.

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‫And that will make a lot more sense as soon as we go into Boolean.

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‫So we will have examples of booleans as well.

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‫All right.

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‫So next the do while loop and that one is slightly different to the while loop, even though it has

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‫the wild term inside of its name, it's starting with a counter variable as well outside of the loop

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‫itself.

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‫Then you have the do keyword, then the curly brackets, and in there you have the code that you want

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‫to execute multiple times or at least once.

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‫And that's the difference between a do while and a while loop.

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‫The do while loop does first and then it checks at the bottom the condition.

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‫So it will repeat as long as the condition is true, but it will run at least once.

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‫And by the way, you have the counter variable increment here as well, then it executes the code as

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‫long as the condition is met as well.

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‫So the same as the while loop.

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‫Only the difference is here.

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‫As I said, it runs once first and that can be very useful if you, for example, don't know if the

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‫condition is met, but you at least want to run the code because it initializes something or it prepares

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‫something, then you would use a dual loop.

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‫And then finally we have the for each loop and it runs through an array or a list.

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‫It's only as long as there is content.

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‫And that's great because.

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‫If you run a four loop, for example, through an array, what you can get is an array index out of

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‫bounds exception.

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‫And that's something that you don't get with a for each loop.

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‫So that's pretty much an error that you can avoid as long as you use it for each loop.

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‫And finally, more about this in the Arrays chapter.

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‫So we're not going to cover for each loop in this chapter, but we're going to use it as soon as we

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‫get to the array section.

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‫And I just wanted to put it in here so you know that there is a different type of loop as well.

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‫So the for each loop.

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‫Great.

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‫So let's go into the demo and let's get started with some examples.

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‫So see you there.