Xref: utzoo comp.unix.wizards:15167 comp.lang.c:17131
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!lll-winken!uunet!garfield!michael
From: michael@garfield.MUN.EDU (Mike Rendell)
Newsgroups: comp.unix.wizards,comp.lang.c
Subject: Re: How to predict size of outcome of vsprintf?
Message-ID: <5124@garfield.MUN.EDU>
Date: 23 Mar 89 15:29:49 GMT
References: <993@etnibsd.UUCP> <9872@smoke.BRL.MIL> <28831@bu-cs.BU.EDU> <16491@mimsy.UUCP> <24451@watmath.waterloo.edu>
Reply-To: michael@garfield.UUCP (Mike Rendell)
Organization: Memorial University of Newfoundland
Lines: 25

In article <wY9m4Hy00UkaI=3Ihb@andrew.cmu.edu> bader+@andrew.cmu.edu
(Miles Bader) writes:
>What I'd really like would be a new function that could act as a basis
>for all the other printf functions, and make it possible to emulate
>them in nice ways.
>
>I would make it a varargs function that takes a bounded output buffer
>and is restartable at the point where it stops due to running into the
>end of the buffer.

I wrote a version of doprnt() which does something like this.  Instead
of taking a FILE * argument it's passed a function pointer and a
"generic argument" (void/char *).  new_doprnt() fills up a stack buffer
and calls the function (which takes the same arguments as fwrite()) to
deal with it.  This makes printf() and a bounds checking sprintf() (or
a re-alloc()ing sprintf()) easy to write as well as providing a simple
method for programmers to hook into it.  I've used it in some screen
based programs to page output and in some stand alone programs to do
output to a console.  The only draw back is that it doesn't handle
%[egf] - but who needs those anyway :-).

Mike Rendell				Department of Computer Science
michael@garfield.mun.edu		Memorial University of Newfoundland
uunet!garfield!michael			St. John's, Nfld., Canada
 (709) 737-4550				A1C 5S7