Xref: utzoo comp.lang.c:35040 comp.lang.c++:10993
Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!srhqla!demott!kdq
From: kdq@demott.com (Kevin D. Quitt)
Newsgroups: comp.lang.c,comp.lang.c++
Subject: Pointer arithmetic
Message-ID: <1991Jan5.001607.5915@demott.com>
Date: 5 Jan 91 00:16:07 GMT
Reply-To: kdq@demott.COM (Kevin D. Quitt)
Organization: DeMott Electronics Co., Van Nuys CA
Lines: 35


    I originally posted to comp.lang.c++ (don't know how it got there):

>    What about the subtraction of pointers to get a constant?  I discovered
>that gcc does not allow:
>
>	int = strchr( string, char ) - &string;
>
>to determine the position of char within string.  Is there a (good) reason
>for disallowing this?  BTW, Microsoft C *does* accept this.


    I rapidly received two responses indicating that the & was the problem.
(Nobody picked on using int and char as variables :-)


    The & was "artistic" in my example.  Microsoft C does allow &string,
but provides a warning that the ampersand is ignored.

    The actual code is:


const unsigned char *chars   = "some string"
unsigned char pass[];

    c   = strchr( chars, toupper( pass[ i ]) ) - chars + 1;


    gcc would not accept this no matter what I did.

-- 
 _
Kevin D. Quitt         demott!kdq   kdq@demott.com
DeMott Electronics Co. 14707 Keswick St.   Van Nuys, CA 91405-1266
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