I'm fairly new to programming. I'm doing an undergrad ENG degree and one of my first year mandatory courses is programming. It's my first time ever doing it so I don't know much yet. I'm currently learning C++. I'm in the middle of working on a problem that pretty much involves me making a calculator. A lot of my variable types are either int or double. If I have some while loops set up so if the user puts in an incorrect number it tells them to reenter, ie putting a a value in for sin^-1 that is greater than 1. However if I put a character in my program crashes. In the question it isn't mandatory that my calculator can handle this but I feel like my code is very unstable. How do I deal with this problem?