Problem with 'struct' module

Matt Feinstein nospam at here.com
Tue Jun 14 16:37:12 CEST 2005


On Tue, 14 Jun 2005 14:24:56 -0000, Grant Edwards <grante at visi.com>
wrote:

>
>Your example is not using standard alignment.  It's using
>native alignment:
>
>    By default, C numbers are represented in the machine's native
>    format and byte order, and properly aligned by skipping pad
>    bytes if necessary (according to the rules used by the C
>    compiler).
>
>    Alternatively, the first character of the format string can
>    be used to indicate the byte order, size and alignment of
>    the packed data, according to the following table:
>
>       Character    Byte order            Size and alignment
>         @            native                   native
>         =            native                   standard
>         <            little-endian            standard
>         >            big-endian               standard
>         !            network (= big-endian)   standard
>
>    If the first character is not one of these, "@" is assumed.
>    
>    Native byte order is big-endian or little-endian, depending
>    on the host system. For example, Motorola and Sun
>    processors are big-endian; Intel and DEC processors are
>    little-endian.
>
>    Native size and alignment are determined using the C compiler's
>    sizeof expression. This is always combined with native byte
>    order.
>
>    Standard size and alignment are as follows: no alignment is
>    required for any type (so you have to use pad bytes); short is
>    2 bytes; int and long are 4 bytes; long long (__int64 on
>    Windows) is 8 bytes; float and double are 32-bit and 64-bit
>    IEEE floating point numbers, respectively.
>
>    Note the difference between "@" and "=": both use native
>    byte order, but the size and alignment of the latter is
>    standardized. 

Thanks. I clearly missed the point of the explanation...

Matt Feinstein

--
There is no virtue in believing something that can be proved to be true.



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