Struct padding (was blank subject)

On 9/26/06, Kirkwood, David A <DAVID.A.KIRKWOODsaic.com> wrote:
> I have an application that works perfectly in a 32 bit
environment, but
> does not in a 64 bit environment. I believe
>
> The problem has to do with a structure defined as
>
>             Struct  x {
>
>                         Short aaa
>                         Short bbb
>                         Char something[12]
>                         Long lll
>                         Long mmm
>             }
>
> Sorry about the capitalization.... I'm condemned to
using exchange /
> outlook.
>
> After the program starts, I look at the  short
variables above and they
> are initialized to hex 2020 (both) which are spaces if
they were
> characters. Since this structure is initialized with a
pointer to is (
> and its components ) I wonder if in the 64 bit
environment I have to
> manually pad out the size(s) to even 64 bit boumderies?

How are you initializing the structure?

You usually shouldn't depend on the layout of structures. 
There are
cases in which it is necessary, but it is usually better to
avoid.  If
you're trying to write the memory region of this structure
to a file
on a 32-bit machine and read it on a 64-bit machine it 
would be
better to write marshal/unmarshal functions to transform the
structure
to/from a platform independent representation.
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