The va_arg, va_end, and va_start routines are macros that provide a portable way to access the arguments to a function when the function takes a variable number of arguments. Two versions of the macros are available: the macros defined in the VARARG.H include file, which are compatible with the UNIX System V definition, and the macros defined in STDARG.H, which conform to the ANSI C standard.
| Routine | Use |
| va_arg | Retrieves argument from list |
| va_end | Resets pointer |
| va_start | Sets pointer to beginning of argument list |
For more information on the differences between the two versions and for an explanation of how to use the macros, see their descriptions in Part 2 of this book.