Path: utzoo!utgpu!attcan!uunet!yale!wald-david
From: wald-david@CS.YALE.EDU (david wald)
Newsgroups: comp.lang.c
Subject: Re: A cast pointer is NOT an lvalue!? (ANSI C)
Keywords: X3J11, pointers, cast, lvalue
Message-ID: <42234@yale-celray.yale.UUCP>
Date: 4 Nov 88 19:21:37 GMT
References: <479@midgard.mn.org> <10034@socslgw.csl.sony.JUNET>
Sender: root@yale.UUCP
Reply-To: wald-david@CS.YALE.EDU (david wald)
Organization: Yale University Computer Science Dept, New Haven CT  06520-2158
Lines: 27

In article <10034@socslgw.csl.sony.JUNET> diamond@csl.sony.JUNET (Norman Diamond) writes:
>In article <479@midgard.mn.org>, dal@midgard.mn.org (Dale Schumacher) writes:
>> I used a pointer cast construct like this:
>>
>>    value = *((long *) argp)++;
>
>If you wanted to increment argp by the length of a (long *), then you
>have to do:
>
>     value = *(long *) argp;
>     argp += (sizeof (long *)) / (sizeof argp);
>
>which cannot give a correct result if sizeof (long *) is not a
>multiple of sizeof (int *).

How about:

    value = *(long *)argp;
    argp = (argtype *)((char *)argp + sizeof(long *));

where argtype is the type of *argp?


============================================================================
David Wald                                              wald-david@yale.UUCP
						       waldave@yalevm.bitnet
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