boolean arrays

[Amira]

Hello there,

I need to store arrays as bit-vectors meaning that i.e. m entries are
stored in a single word on a machine with word size m. I am working on
C++ in unix environement. For any help I am very grateful!

Kind Regards,
amira

[Ben Pope]

Amira wrote:

Hello there,

I need to store arrays as bit-vectors meaning that i.e. m entries are
stored in a single word on a machine with word size m. I am working on
C++ in unix environement. For any help I am very grateful!

Take a look at:

std::vector<bool>
std::bitset<m>

Ben Pope
--
I'm not just a number. To many, I'm known as a string...

[Dietmar Kuehl]

Ben Pope wrote:

Take a look at:

std::vector<bool>
std::bitset<m>

Neither of which is guaranteed to use a compact representation. The
interfaces of these two classes allow a compact representation,
however.
--
<mailto:di***********@yahoo.com> <http://www.dietmar-kuehl.de/>
<http://www.eai-systems.com> - Efficient Artificial Intelligence

[Ferdi Smit]

Ben Pope wrote:

Amira wrote:

Hello there,

I need to store arrays as bit-vectors meaning that i.e. m entries are
stored in a single word on a machine with word size m. I am working on
C++ in unix environement. For any help I am very grateful!

Take a look at:

std::vector<bool>
std::bitset<m>

Ben Pope

Don't use std::vector<bool>, it is not an STL conforming container, and
afaik it is (soon to be) deprecated. Either use bitset, or
boost::dynamic_bitset.

--
Regards,

Ferdi Smit (M.Sc.)
Email: Fe********@cwi.nl
Room: C0.07 Phone: 4229
INS3 Visualization and 3D Interfaces
CWI Amsterdam, The Netherlands

[Dietmar Kuehl]

Ferdi Smit wrote:

Don't use std::vector<bool>, it is not an STL conforming container,
Nor could any other container providing a compact representation
of Boolean be a conforming STL container: the element access, be
it by the index operator or the iterator dereference, is required
to provide a reference but there is no such thing as bit reference
in C++. Unless the STL requirements are changed (which is likely
although the details are not yet fixed), you cannot have both a
compact representation of Booleans and a conforming container.
However, if the requirements are changed, 'std::vector<bool>' will
likely become a suitable STL container.
and afaik it is (soon to be) deprecated.

There are some who dislike 'std::vector<bool>' and want it
deprecated. Since this does not solve the actual problem, i.e.
the inability to use sequences of r-values which are also important
in other situations than accessing bits, I doubt that
'std::vector<bool>' is going to be deprecated. I have, however, no
real idea on how the route towards having different versions of
library components will look like.
--
<mailto:di***********@yahoo.com> <http://www.dietmar-kuehl.de/>
<http://www.eai-systems.com> - Efficient Artificial Intelligence

[Marcus Kwok]

Amira <pa********@gmail.com> wrote:

I need to store arrays as bit-vectors meaning that i.e. m entries are
stored in a single word on a machine with word size m. I am working on
C++ in unix environement. For any help I am very grateful!

As others have mentioned, you can try std::vector<bool> or
std::bitset<>. However, if these do not satisfy your requirements, then
you can use unsigned integral types and bitwise operators.

--
Marcus Kwok

[Michiel.Salters]

Ferdi Smit wrote:

Ben Pope wrote:

Amira wrote:

Hello there,

I need to store arrays as bit-vectors meaning that i.e. m entries are
stored in a single word on a machine with word size m. I am working on
C++ in unix environement. For any help I am very grateful!

Take a look at:

std::vector<bool>
std::bitset<m>

Ben Pope

Don't use std::vector<bool>, it is not an STL conforming container

The topic starter is looking for a container which due to the
requirements
cannot be an STL conforming container. Any other alternative suggested
will have exactly the same "problem" or fail to meet the stated
requirements.

HTH,
Michiel Salters

[Ferdi Smit]

Mi*************@tomtom.com wrote:

The topic starter is looking for a container which due to the
requirements
cannot be an STL conforming container. Any other alternative suggested
will have exactly the same "problem" or fail to meet the stated
requirements.

Any alternative container will not claim to be an STL container, nor
look like one. Nobody will be tempted to use it's iterators (if they
even exist) as input to algorithms. (and we've discussed this before :) )
--
Regards,

Ferdi Smit (M.Sc.)
Email: Fe********@cwi.nl
Room: C0.07 Phone: 4229
INS3 Visualization and 3D Interfaces
CWI Amsterdam, The Netherlands

[Michiel.Salters]

Ferdi Smit wrote:

Mi*************@tomtom.com wrote:

> The topic starter is looking for a container which due to the
requirements
cannot be an STL conforming container. Any other alternative suggested
will have exactly the same "problem" or fail to meet the stated
requirements.

Any alternative container will not claim to be an STL container, nor
look like one. Nobody will be tempted to use it's iterators (if they
even exist) as input to algorithms. (and we've discussed this before :) )

Actually, you can use vector<bool> iterators as input to STL
algorithms.

HTH,
Michiel Salters