I get this error message when trying to build my program
Undefined symbols for architecture x86_64: "CustomerData::CustomerData()", referenced from: PreferredCustomer::PreferredCustomer() in main.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation)
How do i fix this error? I am running c++ on xcode.