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Hey, welcome to today's bonus example.

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In the code experiment video you understood the difference between syntax errors and exceptions.

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Now there is another type of issue which neither the grammar checker or the interpreter.

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Nor the interpreter itself can capture.

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These are more logical issues which only humans can spot in a program, and for that you need to use

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different tools.

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So to discover what these issues are.

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Exactly.

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I will create a program which asks the user to enter the dimensions of a rectangle, and the program

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should output the area of the rectangle.

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So that would be something like.

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Width is equal to input.

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You ask the user to enter the rectangle width.

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Same for length.

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And so you want to convert this into floats so that you capture a number instead of strings, so convert

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the entire input function.

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Put it inside, float inside the parentheses over the float function.

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Event area would be equal to width times length.

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And you print out the area.

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So far, so good.

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So you run the program, you enter for for width five for length, and you get 20.

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But if the user enters four four with using a word instead of a number, then we would get this value

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error.

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So we want to tell the user, Oh, you need to enter an actual number.

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So for that of course we use try and accept as you learned already.

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So what we do is we indent all these lines and we put them inside.

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I try.

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Statements and.

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So we expect an error to happen in any of these, and that is a value error.

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If that happens, then we print out Please enter a number and note that we don't need the continuous

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statements here because we are not inside a wire loop.

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So that should be enough.

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Let's try again for and we have this.

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Please enter a number.

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So far so good.

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So we were able to successfully use try, accept.

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To catch a potential error that the user might trigger.

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But what if we don't want the user to enter?

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For example, if we don't want the user to enter five four with and the same number for length.

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So the program will say 25, but what if we want the program?

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To display a message to tell the user, Oh, wait, that is a square.

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And we we don't accept square calculations of various in our program.

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So we want to to show a message to the user.

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Of course, the try accept block would not accept that would not be able to to handle such a delicate

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requirements because that that is not an error logically for the interpreter that is fine the interpreter

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is simply multiplying two numbers, but this is an issue.

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We should handle it in another way.

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Now that is where if elif else conditional blocks come in handy again.

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In this code, we would write the if conditional after we get the width and the length so we could check

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if width is equal to length.

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And if that's the case.

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We exit the program with a message, we say.

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That's looks like a square.

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You could also live this empty and include a print function here and say here that that looks like a

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square.

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But this is.

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Less code.

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So this exit function now will.

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Break the program will interrupt it and we will print out this.

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String in the command line.

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So let's try it.

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Five.

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Five.

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And we get this.

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That looks like a square.

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The command line here in pie chart is also able to highlight this in red because it's being printed

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out by that exit function.

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So if you don't want that color, then you should use prints here.

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And that put that as I told you inside print.

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So what's going on here?

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Well, this is what happens.

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So we ask the user to answer some inputs.

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If there is an error.

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Then this will be executed.

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So if there is a value error, actually that's then this will be executed.

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If there is no error in here and in here as well.

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Then here the if conditional will check those two values.

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So you see that an if conditional can be used and it can be used without Elif and else.

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Here.

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It was not necessary to have leave or else.

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So and if conditional can be used when you want to check or check values, when you want to check conditions

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which do not produce errors.

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So they are programmatically correct.

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But.

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The product is not acceptable from us.

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So the requirements, for example, here, we don't want users for some reason to enter square dimensions.

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So we tell them, Oh, we don't accept that.

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That looks like a square.

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So if conditionals do not catch errors.

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They check values.

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That's something I wanted you to keep in mind.

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And that's what I was trying to demonstrate with this example.

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So the difference between tri accept and if conditionals.

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Thanks for following this and I'll talk to you later.