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.

Tuesday, January 10, 2012

99 ways to program a hex, Part 2: K&R C

One rule I've set for myself: the output of each program shall be the same (if at all possible). And the baseline for the output is yesterday's version. It's also a useful test—if the output doesn't match, there's a bug somewhere. Other than that, anything goes.

Today's code is written using a style known as “K&R C.”

/*************************************************************************
*
* 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
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* 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: sean@conman.org
*
*************************************************************************/

/* Style: K&R C */

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

#define LINESIZE	  16

/****************************************************************/

main(argc,argv)
char **argv;
{
	int i;
	FILE *fp;
  
	if (argc == 1)
		do_dump(stdin,stdout);
	else {
		for (i = 1 ; i < argc ; i++) {
			fp = fopen(argv[i],"rb");
			if (fp == NULL) {
				perror(argv[i]);
				continue;
			}

			printf("-----%s-----\n",argv[i]);
			do_dump(fp,stdout);
			fclose(fp);
		}
	}

	return 0;
}

/******************************************************************/

do_dump(fpin,fpout)
FILE *fpin,*fpout;
{
	char buffer[BUFSIZ],ascii[LINESIZE + 1],*pbyte;
	int offset = 0,bread,j,i;
  
	while((bread = fread(buffer,1,BUFSIZ,fpin)) > 0) {
		pbyte = buffer;
		while (bread > 0) {
			fprintf(fpout,"%08lX: ",(unsigned long)offset);
			j = 0;
			do {
				fprintf(fpout,"%02X ",(unsigned char)*pbyte);
				if (*pbyte >= ' ' && *pbyte <= '~')
					ascii [j] = *pbyte;
				else
					ascii [j] = '.';
				pbyte++;
				offset++;
				j++;
				bread--;
			} while ((j < LINESIZE) && (bread > 0));
			ascii [j] = '\0';
			if (j < LINESIZE) {
				for (i = j ; i < LINESIZE ; i++) 
					fprintf(fpout,"   ");
			}
			fprintf(fpout,"%s\n",ascii);      
		}
    
		if (fflush(fpout) == EOF) {
			perror("output");
			exit(1);
		}
	}
}

/***************************************************************/

The term “K&R” is still used to refer to a particular style of writing C code (which I personally can't stand, but that's me)—the placement of opening braces, the severe indentation and often times a vowel impairment in names (which I didn't go for here).

But the term can also refer to code written before C was first standardized in 1989 (that is known as “ANSI C” or “C89”). While you had to always declare all your variables, function parameters, on the other hand, only had to be mentioned and unless otherwise noted, were assumed to be of type int. The same goes for the function return value—unless otherwise noted, all functions return a type of int.

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