Adding Errors.h and Errors.c. Errors.h is used to enumerate all the different error codes in your given application. Error.c provides the printError function as define in Errors.h. Errors.h/.c use the "XMACROS" technique to generate enums for the different error types as well as printing code for the given errors. The user should only have to add their own error names to the ERROR_NUMBERS list by following the example provided by NO_ERROR, and INPUT_CANNOT_BE_NEGATIVE error the macros do the rest.