Description

   You can execute multiple traversals of the argument list, each
   delimited by va_start . . . va_end. The va_end function sets ap
   equal to NULL.

   When using this function to write portable applications, include
   the <stdarg.h> header file (defined by the ANSI C standard), not
   the <varargs.h> header file, and use va_end only in conjunction
   with other routines defined in <stdarg.h>.

   For an example of argument-list processing using the <stdarg.h>
   functions and definitions, see the "Character, String, and
   Argument-List Functions" chapter of the VSI C RTL Reference
   Manual.