• Orgoton <orgoton mindless.com> Feb 07 2007
• Frits van Bommel <fvbommel REMwOVExCAPSs.nl> Feb 07 2007
• Tomas Lindquist Olsen <tomas famolsen.dk> Feb 07 2007
• Sean Kelly <sean f4.ca> Feb 07 2007

Orgoton <orgoton mindless.com> writes:

When I declare

bit flags[120];

How much memory does this consure? 120 Bytes or 120 bits (packing).
It would be a pain to make something like "long flags1, flags2..." and "if
(flags1 & FLAGMASK) ..." to conserve memory.

Frits van Bommel <fvbommel REMwOVExCAPSs.nl> writes:

Orgoton wrote:
 When I declare
 
 bit flags[120];
 
 How much memory does this consure? 120 Bytes or 120 bits (packing).
 It would be a pain to make something like "long flags1, flags2..." and "if
(flags1 & FLAGMASK) ..." to conserve memory.


It used to only consume 120 bits, when 'bit' was still a basic type.
There were some issues with that though, so now 'bit' is just a 
backwards-compatibility alias to 'bool'. Since 'bool' is a 1-byte type 
(typically) that means it'll consume 120 bytes.

Tomas Lindquist Olsen <tomas famolsen.dk> writes:

Frits van Bommel wrote:

 Orgoton wrote:
 When I declare
 
 bit flags[120];
 
 How much memory does this consure? 120 Bytes or 120 bits (packing).
 It would be a pain to make something like "long flags1, flags2..." and
 "if (flags1 & FLAGMASK) ..." to conserve memory.


 It used to only consume 120 bits, when 'bit' was still a basic type.
 There were some issues with that though, so now 'bit' is just a
 backwards-compatibility alias to 'bool'. Since 'bool' is a 1-byte type
 (typically) that means it'll consume 120 bytes.


As a note to this you can use std.BitArray in phobos to have a true bit
array.
Not sure what the Tango equivalent is.

http://digitalmars.com/d/phobos/std_bitarray.html

Sean Kelly <sean f4.ca> writes:

Tomas Lindquist Olsen wrote:
 Frits van Bommel wrote:
 
 Orgoton wrote:
 When I declare

 bit flags[120];

 How much memory does this consure? 120 Bytes or 120 bits (packing).
 It would be a pain to make something like "long flags1, flags2..." and
 "if (flags1 & FLAGMASK) ..." to conserve memory.


 There were some issues with that though, so now 'bit' is just a
 backwards-compatibility alias to 'bool'. Since 'bool' is a 1-byte type
 (typically) that means it'll consume 120 bytes.


 As a note to this you can use std.BitArray in phobos to have a true bit
 array.
 Not sure what the Tango equivalent is.


tango.core.BitArray.  The implementation is essentially the same.


Sean