hi,

is there a way to stuff the 8 bytes of a long into a byte array other than to use a union to achive that?

cheers
jc

jc wrote:
> hi,
> 
> is there a way to stuff the 8 bytes of a long into a byte array other than to use a union to achive that?
> 
> cheers
> jc

Take the address, cast to byte, deref byte by byte:

    (cast(ubyte*)&the_long)[0];
    (cast(ubyte*)&the_long)[1];
    (cast(ubyte*)&the_long)[2];
    ...

--bb

Bill Baxter wrote:
> jc wrote:
>> hi,
>>
>> is there a way to stuff the 8 bytes of a long into a byte array other than to use a union to achive that?
>>
>> cheers
>> jc
> 
> Take the address, cast to byte, deref byte by byte:
> 
>     (cast(ubyte*)&the_long)[0];
>     (cast(ubyte*)&the_long)[1];
>     (cast(ubyte*)&the_long)[2];
>     ...

Which means that you can go:

byte[] array = (cast(ubyte*)&the_long)[0..8];

if you want an actual array.

Regan

Bill Baxter wrote:

> jc wrote:
>> hi,
>> 
>> is there a way to stuff the 8 bytes of a long into a byte array other than to use a union to achive that?
>> 
>> cheers
>> jc
> 
> Take the address, cast to byte, deref byte by byte:
> 
>      (cast(ubyte*)&the_long)[0];
>      (cast(ubyte*)&the_long)[1];
>      (cast(ubyte*)&the_long)[2];
>      ...
> 
> --bb

Does gdc run on any little endian machines?  I'm not sure which way arrays grow on such machines, but I think this could would give the reverse byte order of a big endian machine.

Jason House wrote:
> Bill Baxter wrote:
> 
>> jc wrote:
>>> hi,
>>>
>>> is there a way to stuff the 8 bytes of a long into a byte array other
>>> than to use a union to achive that?
>>>
>>> cheers
>>> jc
>> Take the address, cast to byte, deref byte by byte:
>>
>>      (cast(ubyte*)&the_long)[0];
>>      (cast(ubyte*)&the_long)[1];
>>      (cast(ubyte*)&the_long)[2];
>>      ...
>>
>> --bb
> 
> Does gdc run on any little endian machines?  I'm not sure which way arrays
> grow on such machines, but I think this could would give the reverse byte
> order of a big endian machine.

Yep.  Order most definitely depends on endianness.  Intel is little endian.  If you're planning on sending those bytes over a network you'd better swap em if you've got version(LittleEndian).

--bb

"Jason House" <jason.james.house@gmail.com> wrote in message news:fipgc3$5ni$1@digitalmars.com...
<snip>
> Does gdc run on any little endian machines?  I'm not sure which way arrays
> grow on such machines, but I think this could would give the reverse byte
> order of a big endian machine.

Array indexes always follow the sign convention of memory addresses.  The basic difference between big-endian and little-endian machines is which way the bytes of a number go relative to this sign convention.  So yes.

As such, accessing an integer as an array of bytes is a common technique for converting between little-endian and big-endian byte orders.

Stewart.

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