hi,how to define a bitstring type in c/c++?

[wwj]

hello,everyone.I am a new one here.I want to know how to define a
bitstring type in c/c++? and can specify its length.Then I can use it
like:
bitstring a[6]='100111' ;or so.
thank you very much

[Richard Heathfield]

wwj wrote:

hello,everyone.I am a new one here.I want to know how to define a
bitstring type in c/c++? and can specify its length.Then I can use it
like:
bitstring a[6]='100111' ;or so.

This newsgroup is for C questions. For C++ questions, please ask in
comp.lang.c++ (where the answer is very different).

The typical C solution is to define an array of unsigned char, and use some
macros to do the CHAR_BIT multiply for you.

See if you can work out how these work. If you can't, see if you can just
work out how to use them (a rather easier task).

#include <limits.h>

#define SET_BIT(a, n) (a)[(n) / CHAR_BIT] |= \
(unsigned char)(1U << ((n) % CHAR_BIT))
#define CLEAR_BIT(a, n) (a)[(n) / CHAR_BIT] &= \
(unsigned char)(~(1U << ((n) % CHAR_BIT)))
#define TEST_BIT(a, n) (((a)[(n) / CHAR_BIT] & \
(unsigned char)(1U << ((n) % CHAR_BIT))) ? 1 : 0)


--
Richard Heathfield : bi****@eton.powernet.co.uk
"Usenet is a strange place." - Dennis M Ritchie, 29 July 1999.
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html
K&R answers, C books, etc: http://users.powernet.co.uk/eton

[wwj]

Thank you very much!

Richard Heathfield <do******@address.co.uk.invalid> wrote in message news:<bn**********@sparta.btinternet.com>...

wwj wrote:

hello,everyone.I am a new one here.I want to know how to define a
bitstring type in c/c++? and can specify its length.Then I can use it
like:
bitstring a[6]='100111' ;or so.

This newsgroup is for C questions. For C++ questions, please ask in
comp.lang.c++ (where the answer is very different).

The typical C solution is to define an array of unsigned char, and use some
macros to do the CHAR_BIT multiply for you.

See if you can work out how these work. If you can't, see if you can just
work out how to use them (a rather easier task).

#include <limits.h>

#define SET_BIT(a, n) (a)[(n) / CHAR_BIT] |= \
(unsigned char)(1U << ((n) % CHAR_BIT))
#define CLEAR_BIT(a, n) (a)[(n) / CHAR_BIT] &= \
(unsigned char)(~(1U << ((n) % CHAR_BIT)))
#define TEST_BIT(a, n) (((a)[(n) / CHAR_BIT] & \
(unsigned char)(1U << ((n) % CHAR_BIT))) ? 1 : 0)