Exception handling

- [Narrator] Now if you're paying attention…in the last clip, you'll have noticed…that prompt actually isn't an ideal function…if you give it wacky values.…Let's try prompt minus one.…There are minus one items,…well does that make any sense at all?…So maybe we want to do some exception handling…to protect this function against out of range values.…So we're going to do an imperative if,…in other words an if without a then,…because we don't actually need to do anything else.…I'm going to raise an argument,…so that's a completely normal dot net exception…with the message value can't be less than naught.…

So that's all you need to do to raise an exception,…so just try that out.…Let's go down the happy part first…with prompt2 of one.…That's fine.…By the way I forgot to change the printf n again,…so let us fix that.…Perfect.…And what happens now if we hit it with minus one.…Argument exceptional, though that looks ugly…that's exactly what we wanted to happen.…And by the way, later in the course…we'll be looking at much more elegant ways…