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Date: Fri, 21 Dec 2012 16:37:42 +0100
From: Juan Manuel Guerrero <juan DOT guerrero AT gmx DOT de>
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To: djgpp AT delorie DOT com
Subject: Question about va_* macros
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Reply-To: djgpp AT delorie DOT com

I am interesting in recognize the end of the argument list of functions like
printf and scanf when they are accessed using va_* macros.  I have traversed
the list (stack) using va_arg and observed that the list seems to end with a
NULL pointer.  The question arises if the finalizing of the list with a NULL
pointer can be taken for granted or not.  Please note that I am aware that
info doc of the va_* macros tells that the user must provide a mechanism to
determinate the end of the list usually either by a NULL pointer or by some
counter or something else.  I am especially interested in how it works for
_doprnt and _doscan.

TIA

Juan M. Guerrero