13.2.2 Initialize variable argument list

Synopsis

     #include <varargs.h>
     va_list ap;
     va_start(ap);

Description
With the varargs.h macros, use va_start to initialize a data structure ap to permit manipulating a variable argument list. ap must have the type va_alist.

Returns
va_start does not return a result.

Portability
va_start is also defined as a macro in ANSI C, but the definitions are incompatible; the ANSI version has another parameter besides ap.