macros

i have this in a header file:

Code:

...

#define IND_BIT (N) ((N) / NUM_BITS)
/* Find array index for Nth bit */

#define POS_BIT (N) ((N) % NUM_BITS)
/* Find position of Nth bit */

#define SET_BIT (barr, N) ((barr)[IND_BITS(N)] |= (bitarr)1 << POS_BITS(N))
/* Set Nth bit */
...

and this source file:

Code:

#include <stdio.h>
#include "ba.h"

#define M 10

int main(void)
{
  bitarr a[SIZ_BITS(M)] = {0};
  int i;


  SET_BIT (a, 5);

  for (i = 0; i < M; i++)
    if ( TST_BIT(a, i) )
      printf("%dth bit set\n",i);

  return 0;
}

What's the problem?
I get these errors:

Code:

bitarr.c:8: `N' undeclared (first use in this function)
bitarr.c:8: (Each undeclared identifier is reported only once
bitarr.c:8: for each function it appears in.)
bitarr.c:12: `barr' undeclared (first use in this function)
bitarr.c:15: called object is not a function
bitarr.c:15: called object is not a function
bitarr.c:16: syntax error before "printf"

remove spaces before the first (

#define IND_BIT (N) ((N) / NUM_BITS)

=>

#define IND_BIT(N) ((N) / NUM_BITS)

#define IND_BIT (N) ((N) / NUM_BITS)

You're not allowed spaces between the macro name, and the opening (

thanks.
only one error left
bitarr.c:16: syntax error before "printf"

heres' TST_BIT:

Code:

#define TST_BIT(barr, N) ((barr)[IND_BITS(N)] & ((bitarr)1 << POS_BITS(N))

Originally Posted by viaxd

i have this in a header file:
<...>

Many things are missing in this code... Try this :

Code:

#include <limits.h>

#define NUM_BITS CHAR_BIT

#define IND_BITS(N) ((N) / NUM_BITS)
/* Find array index for Nth bit */

#define POS_BITS(N) ((N) % NUM_BITS)
/* Find position of Nth bit */

#define SET_BIT(barr, N) ((barr)[IND_BITS(N)] |= ((bitarr)1 << POS_BITS(N)))
/* Set Nth bit */

#define TST_BIT(barr, N) ((barr)[IND_BITS(N)] & ((bitarr)1 << POS_BITS(N)))
/* Test Nth bit */

#define SIZ_BITS(n) (1 + (n) /sizeof (bitarr))

typedef unsigned char bitarr;

#include <stdio.h>

#define M 10

int main (void)
{
   bitarr a[SIZ_BITS (M)] =
   {0};
   int i;

   SET_BIT (a, 5);

   for (i = 0; i < M; i++)
   {
      if (TST_BIT (a, i))
      {
         printf ("%d%s bit set\n"
                , i + 1
                , (i + 1) == 1 ? "st"
                : (i + 1) == 2 ? "nd"
                : (i + 1) == 3 ? "rd"
                               : "th"
                );
      }
   }

   return 0;
}

thanks a lot, it works now