Re: New datatype addition to gcc

glen herrmannsfeldt <gah@ugcs.caltech.edu> wrote:
>Structures are allowed to have padding for alignment.


But otherwise they are required to be contiguous, unfortunately.
What's more, there is a deeply-ingrained assumption that all objects
can be accessed as arrays of bytes.


>...Casting pointers to a different type and
>dereferencing them is not guaranteed to work, either.


Unfortunately, certain cases *are* guaranteed to work -- like casting
"struct foo *" to "unsigned char *" for purposes of doing I/O on it:


    When a pointer to an object is converted to a pointer to a character
    type, the result points to the lowest addressed byte of the object.
    Successive increments of the result, up to the size of the object,
    yield pointers to the remaining bytes of the object.
(C99, section 6.3.2.3, para. 7)
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
                                                                -- George Herbert | henry@spsystems.net
[Kind of makes me wonder what rock someone's been living under if he designs
a chip with non-uniform memory and expects people to program it in C. -John]

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