va_arg, va_copy, va_end, va_start - handle variable argument list
#include <stdarg.h>
type va_arg(va_list ap, type);
void va_copy(va_list dest, va_list src);
void va_end(va_list ap);
void va_start(va_list ap, argN);
Refer to the Base Definitions volume of IEEE Std 1003.1-2001, <stdarg.h>.