if(arithmetic == 'A' && arithmetic == 'a' && arithmetic == '+')
The comma operator does not do what you think it does - always research how things work rather than assuming :-)
Also, it isn't good practice to use global variables - put them in main().
Hope all goes well !
Actually, the above will not work as well. arithmetic cannot be three things at once. Try || instead of &&.
Sorry, My bad - must be still asleep !
Thanks for the quick responses, guys. @Ispil's suggestion worked, and now everything's working correctly. Starting to feel like I'm not cut out for this stuff, but whatever, gotta power through lol