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Welcome, everybody, very happy that you're here with me and we're going to talk about the second part

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of exceptions and error handling so and the previous video, we have seen several examples of popular

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errors that can be raised in Python language.

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And we have seen like what the code that causes these errors to be raised.

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And also we have seen this sibling error which was raised in the terminal below in charm.

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We have seen the name of the error.

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And we also see that it points out to exactly where the error happened.

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So that was kind of the negative part that our code basically can fail and it can stop being executed

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because we also mentioned once by chance encounters an error.

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It basically stops from running.

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So every code that you are going to have below the line that caused the error would not be executed.

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So this is kind of like the pessimist side of the topic of errors.

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But today we're going to talk about the positive side of exceptions because exceptions can be managed

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and basically we can have full control overall code and prevent it from failing.

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So in Python, we have this tri except statement, which will give us the full control once we have

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an error in execution.

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And this part basically tells us that, as we just mentioned, that the immediately the execution stops,

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once it encounters an error, but we can't have a full control of our code and stop it from failing.

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All right.

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And we're going to use the tricep statement to do it.

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So we're going to discuss about the code flow.

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Basically, what are the things that are happening behind the scenes once we use this dry except statement?

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So we're going to see what happens with the code flow and also going to have a quick implementation

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example where we see exactly what happens if an error is encountered in the execution.

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All right.

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So you can see here how dry except looks like you basically going to have a try keyword in some code

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inside it, same as we had in four loops and if statements.

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OK, so here we have dry statement and we have certain code inside it.

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And right after you have a sibling, except and you also going to have some code inside this one as

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well.

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It's important to mention that you have to use these both together.

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There are siblings and if you only write dry and not mentioning except in your code, you are going

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to have an error.

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So always use both of them together.

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Now, let's talk about the dynamics between these two.

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So let's start from here once we run a file that has dry except statement, quote, execution will first

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run what's inside dry.

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So first of all, the code will go inside the dry.

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And if you have any variables or print print statements in here, it will run it.

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Whatever any code you right here, it will run it.

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And then you have two options.

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If no errors would be raised in my statement, the code will completely one, sorry, the call will

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complete the execution within try and we will ignore the part completely.

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OK.

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So if this part in here and so dry, you do not have any errors.

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So it will complete the execution inside dry and will ignore the accept part completely.

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And then whatever is after whatever appears, whatever code appears after dry would also run.

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OK, this is like the usual stuff, you know, like once the cold inside dry will be executed, if you

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have any code here below, it will also be executed.

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OK, so not just going to stop and dry, except like the normal behavior of code.

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If you don't have any errors, it will just simply run.

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All right.

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But if you have an air or reste inside this dry statement right here, the cold will not fail or stop.

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And this is the important point we need to stop and discuss about, because in the previous video we

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have seen, we have created some code which cost us an exception.

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And then the execution basically stopped immediately and it did not continue to run.

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Just wrote to us in the terminal below.

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We have an exception and the code stopped from running.

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But in this case right here, the code that inside Trie had an exception and it did not stop the execution

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basically jumped immediately.

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And it's starting to execute whatever is inside the except.

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OK, so the execution will instantly move to executing of what's inside.

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Except, OK, so this is the whole deal.

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This is how we get full control when having an error during execution, because if having some problematic

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code, we should, you should think about putting the problem code or dangerous code inside dry and

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then if it gets an error it will immediately go to accept and it will continue to execute our program.

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So that part was regardless, regardless of implementation, it basically was a simple code flow explanation.

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What happens inside here and now we're going to see an implementation error of what really happens if

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we're encountering an error in live code.

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All right.

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So this example right here, you can see declaration of try and accept using these two keywords and

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then you have some indention inside attrite, same as you have inside.

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If statements are for loops and just need to have some indention.

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And right here we having this if age is smaller than twenty.

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Yeah.

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The if statement while we see that we did not declare the edge of a variable before, OK, we're just

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using age smaller than twenty, but we did not put any value to age.

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So basically this causes a syntax error.

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OK, this execution of this card will cause a syntax error.

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And this is the first example that we have seen and the list of errors in the previous video.

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But in the previous video, we did not have dry, except we just had this if some number smaller than

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some value.

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We had an exception because we did not declare the variable and then the code stopped from running.

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But this time we're having this variable inside.

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Try and let's try to apply the rules that we have went over here to this example.

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So one basically will happen when the code reaches this if here this print would not be executed.

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As we mentioned that when having this exception in this line right here, it immediately jumps to the

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accept part and the code will execute whatever inside the except ignoring the code that comes after

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the exception right here.

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And try.

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And this exception perhaps here, age variable was not assigned with any value setting value.

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Three now.

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OK, I'm doing whatever I want here.

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I have full control over the code.

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Basically, I recognized that I'm going to have a syntax error here.

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So I immediately know the reasons I wrote here to the end user.

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Whoever runs the program, each variable was not assigned with any value setting value three now.

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And once I encountered this error, basically here I'm giving a value off three to the age variable.

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And then I'm asking again, if age is smaller than 20 and if it's true, then this person is very young.

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So we basically redirect the code.

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Once an error is raised by China will continue the run from what's inside.

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Except I think this covers the dry accept and error handling pretty good.

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The topics we have covered.

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We have seen lots of examples of exceptions and also now we are familiar of how controlling the code

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and stopping from the exceptions of failing our execution.

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All right.

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Let's see the following, the actual regarding our an assignment, the homework assignment regarding

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off tricep.

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And there I will give you a preprepared bulk of code that would raise a certain exception.

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And I would like you to use tricep to overcome from that cold from failing.

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I will see you in the next lecture.

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Thank you.