va_list − variable argument list
Standard C library (libc)
#include <stdarg.h>
typedef /* ... */ va_list;
Used by functions with a varying number of arguments of varying types. The function must declare an object of type va_list which is used by the macros va_start(3), va_arg(3), va_copy(3), and va_end(3) to traverse the list of arguments.
C11, POSIX.1-2008.
C89, POSIX.1-2001.
The following headers also provide va_list: <stdio.h> and <wchar.h>.
va_start(3), va_arg(3), va_copy(3), va_end(3)