I will need to have all the programs to work and compile and work in Tandem. This has never been a case in the past. For example if we have Customer.cpp, Customer.h and Main.cpp. I need the programmer to make them all compile and work together. Also don't include like Customer.cpp in the header. Try and include it in the header of the Customer.h. Please if you need explanation feel free to ask. It is very important we follow that.