The Boston Diaries

The ongoing saga of a programmer who doesn't live in Boston, nor does he even like Boston, but yet named his weblog/journal “The Boston Diaries.”

Go figure.

Thursday, January 19, 2012

99 ways to program a hex, Part 11: C89, const correctness, assertive, GCC extensions

Today's code is identical to part 9 save for one line—it uses a GCC extention to notify the compiler that the do_dump() function accepts NULL pointers, and that it won't throw any exceptions.

* Copyright 2012 by Sean Conner.  All Rights Reserved.
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
* Comments, questions and criticisms can be sent to:

/* Style: C89, const correctness, assertive, GCC extensions */

#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>

#define LINESIZE	  16

static void 	do_dump		(FILE *const,FILE *const) __attribute__((nonnull,nothrow));


int main(const int argc,char *const argv[])
  assert(argc    >= 1);
  assert(argv    != NULL);
  assert(argv[0] != NULL);
  if (argc == 1)
    int i;
    for (i = 1 ; i < argc ; i++)
      FILE *fp;
      fp = fopen(argv[i],"rb");
      if (fp == NULL)


  return EXIT_SUCCESS;


static void do_dump(FILE *const fpin,FILE *const fpout)
  unsigned char  buffer[BUFSIZ];
  unsigned char *pbyte;
  size_t         offset;
  size_t         bread;
  size_t         j;
  char           ascii[LINESIZE + 1];
  assert(fpin  != NULL);
  assert(fpout != NULL);
  offset = 0;

  while((bread = fread(buffer,1,BUFSIZ,fpin)) > 0)
    pbyte = buffer;
    while (bread > 0)
      fprintf(fpout,"%08lX: ",(unsigned long)offset);
      j = 0;
        fprintf(fpout,"%02X ",*pbyte);
        if (isprint(*pbyte))
          ascii [j] = *pbyte;
          ascii [j] = '.';
        pbyte  ++;
        offset ++;
        j      ++;
        bread  --;
      } while ((j < LINESIZE) && (bread > 0));
      ascii [j] = '\0';
      if (j < LINESIZE)
	size_t i;

	for (i = j ; i < LINESIZE ; i++) fprintf(fpout,"   ");
    if (fflush(fpout) == EOF)


Obligatory Picture

[“I am NOT a number, I am … a Q-CODE!”]

Obligatory Contact Info

Obligatory Feeds

Obligatory Links

Obligatory Miscellaneous

You have my permission to link freely to any entry here. Go ahead, I won't bite. I promise.

The dates are the permanent links to that day's entries (or entry, if there is only one entry). The titles are the permanent links to that entry only. The format for the links are simple: Start with the base link for this site:, then add the date you are interested in, say 2000/08/01, so that would make the final URL:

You can also specify the entire month by leaving off the day portion. You can even select an arbitrary portion of time.

You may also note subtle shading of the links and that's intentional: the “closer” the link is (relative to the page) the “brighter” it appears. It's an experiment in using color shading to denote the distance a link is from here. If you don't notice it, don't worry; it's not all that important.

It is assumed that every brand name, slogan, corporate name, symbol, design element, et cetera mentioned in these pages is a protected and/or trademarked entity, the sole property of its owner(s), and acknowledgement of this status is implied.

Copyright © 1999-2024 by Sean Conner. All Rights Reserved.