For assignment #3, you don’t have to worry too much about things like “what if they enter an invalid formatted date?” “What if they type ‘bob‘ for the number of tickets to purchase?” Etc. You do need to make sure to properly handle these two errors, though: attempts to (1) an attempt to purchase a ticket when the flight is sold out, and (2) an attempt to purchase a ticket “in the past.”

Also, just a heads-up to something I would think would be obvious, but which students have messed up on in the past: if there are no tickets yet sold for a particular day’s flight, that should not stop a user from buying (the first) ticket for that day. If you think about it, it would be ridiculous for your program not to allow that — you’d be in an infinite loop, never able to buy tickets for a flight!