Xref: utzoo comp.lang.c:17047 comp.unix.wizards:15109
Path: utzoo!attcan!uunet!husc6!bu-cs!bzs
From: bzs@bu-cs.BU.EDU (Barry Shein)
Newsgroups: comp.lang.c,comp.unix.wizards
Subject: Re: How to predict size of outcome of vsprintf?
Message-ID: <28831@bu-cs.BU.EDU>
Date: 19 Mar 89 15:46:08 GMT
References: <993@etnibsd.UUCP> <9872@smoke.BRL.MIL>
Organization: Boston U. Comp. Sci.
Lines: 19
In-reply-to: gwyn@smoke.BRL.MIL's message of 19 Mar 89 05:52:35 GMT


From: gwyn@smoke.BRL.MIL (Doug Gwyn )
>No.  Sometimes you can accurately predict an upper bound on the output
>string length; for example if the format is "%d" and the numerical
>argument is known to lie between 0 and 5000, the maximum number of
>characters for the *sprintf() output will be 5 (including the null
>byte at the end).

Another way to say that is:

	print_width = LOGx(N) + 1

where x (the log base) is the base to be printed in, 10 for %d, 16 for
%x, 8 for %o etc. And add one for sign (+-) if needed.

But of course that doesn't help a lot except with the simplest
cases (eg. try "%-5.*g").

	-Barry Shein