Date: Tue, 10 Jun 1997 00:22:20 +0930 (CST) From: Michael Smith <msmith@atrad.adelaide.edu.au> To: hackers@freebsd.org Subject: %i conversion in sscanf? Message-ID: <199706091452.AAA29091@genesis.atrad.adelaide.edu.au>
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Hmm. Beating up on some code here (study break 8) I have an
interesting situation where the %i format is not being interpreted as
the author of the code I'm munging obviously believed it should.
To cut a long story short; from sscanf(3) :
i Matches an optionally signed integer; the next pointer must be a
pointer to int. The integer is read in base 16 if it begins with
`0x' or `0X', in base 8 if it begins with `0', and in base 10 oth-
erwise. Only characters that correspond to the base are used.
Ok. Fairly ambiguous. Some test examples :
token: '0x12345678' -> int 0x12345678
token: '0xABCDEF45' -> int 0x7fffffff
Hmm. Not _necessarily_ expected, although it makes reasonable sense.
However, what I wonder is is this "right" by whatever standard governs
sscanf()?
If not, a question. Is -0x12345678 a legitimate numeric represenatation?
If so, how about -0x80000000?
It's "fairly" clear that %i might be expected to convert 0xABCDEF45
to a negative number - Tcl thinks that way :
silver:/tmp>tclsh
% expr 0xABCDEF45
-1412567227
So, a judgement call from the numeric gods, perchance?
--
]] Mike Smith, Software Engineer msmith@gsoft.com.au [[
]] Genesis Software genesis@gsoft.com.au [[
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