FW: changes to zdump.c and zic.c invocations of is.* macros

Olson, Arthur David (NIH/NCI) [E] olsona at dc37a.nci.nih.gov
Thu Dec 8 15:49:57 UTC 2005

-----Original Message-----
From: Robert Elz [mailto:kre at munnari.OZ.AU] 
Sent: Tuesday, December 06, 2005 10:20 PM
To: Arthur David Olson
Cc: tz at lecserver.nci.nih.gov
Subject: Re: changes to zdump.c and zic.c invocations of is.* macros 

    Date:        Tue, 6 Dec 2005 13:35:15 -0500 (EST)
    From:        Arthur David Olson <olsona at elsie.nci.nih.gov>
    Message-ID:  <200512061835.jB6IZFWH007741 at elsie.nci.nih.gov>

  | ! 		while (isascii((unsigned char) *cp) &&

You sometimes do better if you write that as

		while (isascii(*(unsigned char *)cp) &&

It can also be a little clearer what you're intending - there's no
intention here to fetch the char, then convert it to unsigned, all we
want is the 0..255 value that cp points at.

Than again, and I haven't looked at the code again just now to see if it
is practical or not, but an alternative might just be to declare cp as
being unsigned char * right from the start (even if that means that it
needs to stop being an input parameter, and instead be copied from one
which would need to remain char * to avoid changing the API).


ps: I don't think Paul's suggested variation is really the right thing
to do - it is certainly true that it's possible to test for digits by
using  >= '0' && <= '9' tests - but if that's the best way to write it,
that's what isdigit() ought to be doing.     If you want to make it
it is safe to stop the isascii() test if the arg is known to be unsigned
char which after this change, it will be (or EOF, but that's irrelevant

Paul's version may be textually shorter, but with that cp++ side effect
buried in the middle of the && sequence, it is not nearly as easy to

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