I'm teaching myself C, and I've never had to deal with user input before so I need some assistance. For the program I want to create, a user is allowed to input any amount of numbers (no negatives) and any amount of A's B's and/or C's. Letters D-Z are invalid. Example: 54321ABC is valid and 123DEA is invalid.
K&R 2nd edition only seems to talk about user input of int's only, so I'm confused about what to have the input variable be (char, char *, etc)? And how do I validate the input to be only numbers and the letters A, B, and/or C?
I know this is probably incredibly simple, but I'm very new to this language. Thanks for the help.