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‫Well, welcome back.

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‫In this video, we're going to fix the bug that we had and we're going to see how we can figure it out.

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‫So in this example, it's a very basic one.

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‫And we really know that we have this method that does the logic right.

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‫So this is the one that figures out if a friend is a party friend or not.

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‫And that's something that is generally something that will help you to debug because if you know what

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‫a specific method will do, then you can create a breakpoint at that point.

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‫All right.

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‫So if you work in a program that you have never used before or seen before, then you, of course,

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‫need to, first of all, look into it and understand what all of the methods do.

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‫And that's why here, of course, it would be useful to have a summary of what's going on here.

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‫All right.

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‫So explain.

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‫Okay.

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‫What does list do?

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‫What's the summary of this method?

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‫So you can just use triple steps here and then you can add a little summary.

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‫So this is the logic to figure out who is a party friend or who a party friend will be or something

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‫like that.

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‫It's not perfect English here, but I think you understand what the idea is.

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‫So once you do that, you will know, okay.

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‫All right, this is where the logic is.

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‫And our program works by itself, right?

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‫So it's working as intended more or less, except for, of course, that it shows us, the friends,

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‫we have a long name and not the ones with short name.

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‫So most likely the problem lies in the logic how we select something.

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‫So here we could already see.

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‫All right, probably.

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‫This is the method where we have the problem so we can get rid of this breakpoint and this one as well.

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‫And then we can have a look at our method here.

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‫So let's just add a breakpoint and or get party friend method and then we can look into it.

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‫So let's start with it.

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‫And what's important are of course, the values, right?

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‫So we want to know the values.

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‫And in this case, we're interested in shortest name and also maybe in the length here because that's

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‫the logic, right?

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‫So what we would do is we then go to the next step.

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‫And we can see, okay, the list consists of seven values, so that's fine.

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‫So this seems to work.

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‫We have all of our friends in there.

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‫So until that point everything seems to be fine.

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‫Then we go to the next step.

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‫So we have our eye, which is our.

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‫Counter and it's at zero.

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‫All right, that's OC.

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‫And the discount count is at seven, so we can go to the next step.

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‫Now we have a comparison here.

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‫If list I length greater shortest length.

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‫And there we can see the shortest name is Frank.

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‫So that's the one we started with.

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‫Right?

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‫So the list starts with Frank.

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‫So at list I, which is zero, we will have Frank.

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‫So that's fine.

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‫Now let's go to the next step as it seems, this condition in the if statement wasn't true.

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‫All right.

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‫So then we can go to the next iteration or next step and it's comparing again.

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‫Now we can see the list is still seven people.

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‫And then we had a string length get returned with three and the other one was five.

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‫So what's going on here?

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‫We're looking at Joe and Joe should be the next one that's in the list because he has a shorter name

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‫than Frank.

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‫And that's something that we know because we wrote the program.

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‫But for some reason, sure, this name is still Frank.

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‫So then we could at this point realize our them.

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‫All right.

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‫So probably it's that we have a error here.

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‫So we're comparing greater to even though it should be less than all right or smaller than.

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‫And now if we get rid of the breakpoint and we run our program again, then we will see.

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‫Okay, we get the shortest names, Joe and D, Frank and Maria.

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‫All right, so that's great.

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‫So now our program is back free.

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‫Well, and of course, it's not because we still have plenty of problems here.

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‫So one of them is that we have this list with Frank, Joe, Michelle and so forth.

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‫All right.

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‫So we created the list manually so we know what's in there.

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‫But now let's say what we try to do is we try to invite ten people, but our daughter just gave us a

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‫list of seven people.

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‫So let's run this code.

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‫And.

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‫We have an exception.

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‫Perfect.

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‫So that's the great thing about exceptions.

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‫You know that something is wrong with your code and you can fix it because sometimes, as we just saw,

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‫if you don't see the bugs, they are super difficult to fix.

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‫And here it's an argument out of range exception index was out of range must be non negative and less

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‫than the size of the collection.

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‫So you can view details about this.

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‫You can see a little more about this exception and it will tell you all you need to know.

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‫Right.

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‫So a lot of information.

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‫Most of the time it's too much.

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‫But what this says is that we are trying to access an element in the list that is out of our range.

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‫So what could it be?

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‫Well, it could be the list that we're trying to access so we can go here.

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‫And we can see that we have an exception.

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‫We have a list, count zero.

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‫So what's going on?

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‫Why is the list zero?

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‫Because we saw before the list was seven.

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‫Right.

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‫So why is the list suddenly zero?

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‫Because we never really.

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‫We looked at the list and deleted the list.

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‫Right.

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‫Well.

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‫What we did is we removed an element of the list.

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‫So we said List that remove.

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‫And that is a beginner's mistake, so to say, because as I told you earlier, we're passing by reference.

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‫We're not passing by value.

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‫The difference is the following when we say.

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‫That we want to have a list here.

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‫And once this method is called, which is the case here, so get party friends is called here and we

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‫pass a list called friends.

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‫So we pass this list here, which doesn't mean that we pass the values we don't we actually pass the

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‫reference to those values, which means that all of those values, they are somewhere in our memory.

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‫So they they're in the memory of our computer.

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‫Right.

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‫And we're referencing to those values.

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‫So we say, okay, I would like to go to this memory where you have all of your friends.

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‫So I would like to go to Frank, I would like to go to Joe and so forth.

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‫So once we work with this list, for example, we remove an element of that list.

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‫We don't create a copy with the values, and then we go ahead and remove elements from the list.

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‫But we're actually deleting in this memory.

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‫So we're deleting Frank from the list, we deleting Joe from the list.

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‫So you can quite easily see that if you use this for each loop to check out your friends.

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‫Okay, so I'm going to reduce it again so that we can actually see something.

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‫So I'm going through this for each loop.

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‫And as you can see, only Angelina is displayed.

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‫Why only Angelina?

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‫Because Angelina is the seventh in the list, and I just removed six people from the list.

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‫Let's do that again with four people.

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‫Just so you see that Maria, Carlos and Angelina are still there.

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‫So you see see, actually, it's Michelle.

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‫All right.

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‫So even better now we have a very weird situation where it's Michelle, Carlos and Angelina who are

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‫still in the list.

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‫So we are constantly removing someone from the list and that creates a bunch of problems because if

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‫somebody else or if we use this friends list somewhere else, then it will be empty and it will be corrupted.

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‫It will not have the initial values in there, and that's something that we should not do.

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‫So what we can do is we can create a buffer here.

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‫So I'm just going to create a new variable called buffer, and that will be a new list of strings.

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‫And it will be my list, so I'm just going to pass my list that is passed to me at this point.

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‫All right.

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‫And I'm going to store it in buffer.

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‫So it's going to be a new list.

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‫And now what we can see is that we, of course, have to now remove from the buffer.

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‫So we will remove from this copy of the list.

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‫We won't remove from the list itself.

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‫All right.

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‫That's the important differentiation that we have to make.

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‫We are removing from the copy now.

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‫Now, of course, we also have to use the buffer here to get the party front.

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‫All right.

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‫Because otherwise we will never release anything from the list.

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‫That will always be seven people.

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‫So even in this buffer list, it will always be seven people and then it will not work correctly.

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‫All right.

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‫So that we are Frank, Joe, Michel, everything is still in the list.

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‫Okay.

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‫So the for each loop works out well.

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‫And in comparison, what we could do is we could make another for loop and check it out with party friends

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‫just to see if now we only have seven party or three party friends.

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‫So you can see it's actually fourth party friends.

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‫So all of them are in there and Joe and Frank and Maria are also still in there.

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‫So we didn't delete the friends list, we deleted the elements from the buffer list.

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‫And now, of course, we don't need this anymore.

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‫So this was just for testing purposes and to debug.

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‫But now we have a program that works well.

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‫Now you could say, all right, we don't have any bugs anymore.

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‫Well, but we still didn't fix that one bug that we had before, where if we enter ten here.

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‫We would.

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‫Got a bug or an error?

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‫Actually, an argument out of range exception.

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‫So what can we do here?

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‫Because we're trying to access an element that does not exist.

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‫So we're trying to access a list element even though our list is empty.

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‫So list count is zero.

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‫And that is something that we're going to fix in the next video because again, this video is more than

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‫10 minutes and so don't want to make super long videos.

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‫So I'm going to show you how to fix this in the next video because we have plenty of problems that result

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‫from this.

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‫All right.

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‫So let's fix them in the next video.

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‫See you there.