🚀 go-pugleaf

In article <nevin-1902962045260001@150.135.1.79>,
Nevin ":-]" Liber <nevin@CS.Arizona.EDU> wrote:
>In article <kevinbDMv1Br.2C1@netcom.com>, kevin@frobozz.sccsi.com (Kevin
>Brown) wrote:
>
>> You've got to be kidding.  This is kiddie stuff...
>> In case you were wondering, the magic "241 / 100" in the BUFLEN
>> expression comes from log(256), which is the number of base-10 digits
>> required to represent a single byte.
>
>Sorry Kevin, but a "byte" under ANSI C is *not* guaranteed to be 8
>bits.

Ooops....you're right.  Guess I should have looked that one up, eh?
Fortunately, there seems to be a resolution...

>For a bunch of people (Dan Pop, yourself, etc.) claiming that it is
>trivial to write portable ANSI C code, 

I don't think I made that claim, but I will say that writing portable
ANSI C code isn't a *terribly* difficult thing to do...limiting, yes,
but not difficult.

>you are certainly having a very
>tough time getting this code correct.

Well, hang on...that was just a first attempt, so it's hard to say
that I'm "having a very tough time", particularly since I knocked up
the first version in about 5 minutes...

Try this version instead:

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

/*
 * 31/100 ~== log(2) == number of base 10 digits required to store a binary
 * digit.
 */
#define BUFLEN ((sizeof(int) + 1) * CHAR_BIT * 31 / 100 + 3)

char *itoa ( int x )
{
    char *buf, *p, *p2;
    int negative = 0;
    static char nums[] = { '0', '1', '2', '3', '4', '5', '6', '7',
    '8', '9' };

    if ( ! ( buf = malloc(BUFLEN) ) )
        return NULL;
    p = buf + BUFLEN - 1;
    if ( x < 0 )
    {
        x = -x;
        negative = 1;
    }
    *p-- = 0;
    do
        *p-- = nums[x % 10];
    while ( x /= 10 );
    if ( negative )
        *p = '-';
    else
        p++;
    if ( p != buf )
    {
        p2 = buf;
        do
            *p2++ = *p;
        while ( *p++ )
    }
    return buf;
}


This one should be unportable only if CHAR_BIT isn't guaranteed by the
ANSI standard to be defined in limits.h.  I've even taken care of the
issue of non-ASCII character sets.


-- 
Kevin Brown                                     kevin@frobozz.sccsi.com
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