Pergunta de entrevista da empresa Verizon

I always ask, we need a C function to do some string manipulation. We just moved from another system, where this was part of the standard library and it is not there on this system. Here is the prototype, please implement this for us. The exact details change but it involves adding and/or removing strings from an input string. If you have done much C string manipulation, it won't cause any trouble. If not, you will crash and burn and it will be very obvious.