add a char to char*

I can't believe I'm starting a thread about this, but how are you suppose to add a char to a string. I've been using the following method for as long as I can remember.

gcc -Wall gives a warning of “warning: array subscript has type ‘char’”. Even though ch is a f-ing char.

Anyway, my code is not suppose to have any warnings in it at all. What is the proper way of adding a char into a char array if not this way?

re: add a char to char*

This warning is to do with the type of y not the type of ch, explain here although it wonders a little off topic after the first 10 or so posts.