If your C compiler predates ANSI C, you may still be able to use variable argument lists using the macros from the varargs.h header file. These macros resemble their ANSI counterparts, but have important differences in usage. In particular, since traditional C has no declaration mechanism for variable argument lists, two additional macros are provided simply for the purpose of defining functions with variable argument lists.
As with stdarg.h, the type va_list is used to hold a data
structure representing a variable argument list.