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Re: "struct hack" with non-character array[1]

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On 08/19/11 10:28 PM, Hallvard B Furuseth wrote:
> I seem to remember the "struct hack" is safer if the fake
> dynamic array has character type.  If that's right, where/why?

Why should it be?

> Maybe in C99, since the struct hack is undefined in C89?  Or
> real life implementations, nothing to do with the standard?
>
> That is,
>     typedef<char or int>  T;
>     struct hack { Foo foo; T dynamic[1]; };

make that

struct hack { Foo foo; T dynamic[]; };

for C99.

>     struct hack h = malloc(sizeof *h) + sizeof(T)*n;
>     .... use h->dynamic[0..n-1] ...;
> would be safer with T = char than with T = int.

It wouldn't compile with either.  The flexible array member is irrelevant.

-- 
Ian Collins

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"struct hack" with non-character array[1] Hallvard B Furuseth <h.b.furuseth@usit.uio.no> - 2011-08-19 12:28 +0200
  Re: "struct hack" with non-character array[1] Ian Collins <ian-news@hotmail.com> - 2011-08-19 23:15 +1200
    Re: "struct hack" with non-character array[1] Hallvard B Furuseth <h.b.furuseth@usit.uio.no> - 2011-08-19 15:12 +0200
    Re: "struct hack" with non-character array[1] falk@rahul.net (Edward A. Falk) - 2011-08-19 16:41 +0000
  Re: "struct hack" with non-character array[1] Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-08-19 08:01 -0400
  Re: "struct hack" with non-character array[1] James Kuyper <jameskuyper@verizon.net> - 2011-08-19 08:40 -0400
  Re: "struct hack" with non-character array[1] Keith Thompson <kst-u@mib.org> - 2011-08-19 09:41 -0700

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