Char to int using functions

Hello all,

I have a program that imputs some numbers and had 8 different functions that calculate the numbers in some sort of way so in the end I have 8 different numbers. I have managed to get all the functions wroking and the number output are right but the last thing I have to do is output the corresponding characters to the integers and I can't seem to work it out. I have tried so many different things. Should I make another function to perform this or just do it in the main? Please help.

Thanks so much