Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c > #25351

Re: #define BYTES *8

Show all headers | View raw

JohnF wrote:
> 
> Anything wrong with that, i.e., with  #define BYTES *8
> to multiply by 8? It looked a little weird to me, but
> the more obvious #define BYTES(x) ((x)*8) isn't what
> I wanted to write. This was to express units of measurement,
> e.g., int bits = so_many BYTES; rather than
> int bits=BYTES(so_many); . I just wanted to read and write
> it the first way, and my test program
>  #define BYTES *8
>  #include <stdio.h>
>  int main ( int argc, char *argv[] ) {
>   int bytes=(argc<2?1:atoi(argv[1])),
>       bits = bytes BYTES;
>   printf("%d bytes = %d bits\n",bytes,bits);
>   return(0); }
> works fine (and compiles with no -pedantic warnings).
> But that #define BYTES *8 still looks a little funky to me.
> I realize 2+2 BYTES must be written (2+2)BYTES, but is there
> any other kind of "gotcha"?

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>

#define BITS(X)  ((X) * CHAR_BIT)

int 
main (int argc, char *argv[]) 
{
    unsigned bytes = argc < 2 ? 1 : atoi(argv[1]);
    unsigned bits  = BITS(bytes);

    printf("%u bytes = %u bits\n", bytes, bits);

    return 0; 
}

-- 
pete

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

#define BYTES *8 JohnF <john@please.see.sig.for.email.com> - 2012-08-28 07:44 +0000
  Re: #define BYTES *8 Mark Bluemel <mark_bluemel@pobox.com> - 2012-08-28 09:07 +0100
  Re: #define BYTES *8 Keith Thompson <kst-u@mib.org> - 2012-08-28 01:38 -0700
    Re: #define BYTES *8 JohnF <john@please.see.sig.for.email.com> - 2012-08-28 09:21 +0000
      Re: #define BYTES *8 "BartC" <bc@freeuk.com> - 2012-08-28 12:34 +0100
        Re: #define BYTES *8 JohnF <john@please.see.sig.for.email.com> - 2012-08-28 12:23 +0000
    Re: #define BYTES *8 Kenneth Brody <kenbrody@spamcop.net> - 2012-08-29 11:10 -0400
      Re: #define BYTES *8 Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-29 11:36 -0400
        Re: #define BYTES *8 Adrian Ratnapala <raka@scooter.fritz.box> - 2012-08-30 04:01 +0000
        Re: #define BYTES *8 Kenneth Brody <kenbrody@spamcop.net> - 2012-08-30 19:08 -0400
          <OT> Re: #define BYTES *8 Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-30 21:30 -0400
            Re: <OT> Re: #define BYTES *8 Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-08-31 02:49 +0100
              Re: <OT> Re: #define BYTES *8 JohnF <john@please.see.sig.for.email.com> - 2012-08-31 08:32 +0000
                Re: <OT> Re: #define BYTES *8 88888 Dihedral <dihedral88888@googlemail.com> - 2012-08-31 03:55 -0700
              Re: <OT> Re: #define BYTES *8 "BartC" <bc@freeuk.com> - 2012-08-31 10:58 +0100
                Re: <OT> Re: #define BYTES *8 Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-08-31 11:53 +0100
                Re: <OT> Re: #define BYTES *8 "BartC" <bc@freeuk.com> - 2012-08-31 12:39 +0100
                Re: <OT> Re: #define BYTES *8 Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-08-31 15:35 +0100
                Re: <OT> Re: #define BYTES *8 "BartC" <bc@freeuk.com> - 2012-08-31 19:15 +0100
                Re: <OT> Re: #define BYTES *8 Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-08-31 14:39 -0400
            Re: <OT> Re: #define BYTES *8 Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-09-06 15:14 +0300
  Re: #define BYTES *8 "Scott Fluhrer" <sfluhrer@ix.netcom.com> - 2012-08-28 12:24 -0400
    Re: #define BYTES *8 "BartC" <bc@freeuk.com> - 2012-08-28 17:44 +0100
    Re: #define BYTES *8 Keith Thompson <kst-u@mib.org> - 2012-08-28 14:42 -0700
  Re: #define BYTES *8 pete <pfiland@mindspring.com> - 2012-08-28 23:47 -0400
  Re: #define BYTES *8 Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2012-08-29 22:20 -0600
  Re: #define BYTES *8 John Bode <jfbode1029@gmail.com> - 2012-09-06 15:32 -0700
    Re: #define BYTES *8 pete <pfiland@mindspring.com> - 2012-09-06 20:58 -0400
      Re: #define BYTES *8 Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-09-06 21:13 -0400
      Re: #define BYTES *8 Öö Tiib <ootiib@hot.ee> - 2012-09-07 03:00 -0700
        Re: #define BYTES *8 pete <pfiland@mindspring.com> - 2012-09-08 10:00 -0400
    Re: #define BYTES *8 "BartC" <bc@freeuk.com> - 2012-09-07 02:22 +0100
      Re: #define BYTES *8 John Bode <jfbode1029@gmail.com> - 2012-09-07 05:55 -0700
  Re: #define BYTES *8 Tim Rentsch <txr@alumni.caltech.edu> - 2012-09-07 14:20 -0700

csiph-web