Message-ID: <39EAA40B.31B0CA89@eton.powernet.co.uk>
Date: Mon, 16 Oct 2000 07:45:31 +0100
From: Richard Heathfield <binary AT eton DOT powernet DOT co DOT uk>
Organization: Eton Computer Systems Ltd
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Newsgroups: alt.comp.lang.learn.c-c++,comp.os.msdos.djgpp,comp.programming
Subject: Re: Undertaking a programming journey
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ChuckEasttom wrote:
> 
<snip Schildt exposé URLs>
> >
> 
> Something you seem to miss is that the beauty and power of C is the
> fact that it lends itself to a variety of programming styles.  I
> personally liked Schildts books.  I have only read three of them but
> the ones I read I liked.  They where not perfect, but they where good.
> Appearantly a lot of other people do, since they sell so well.

Yes, they do sell well, don't they? So do horoscopes.


Schildt is probably the primary reason that so many C programmers think
main returns void.
Schildt is probably the primary reason that so many C programmers think
fflush(stdin) is a "neat trick".
Schildt is probably the primary reason that so many C programmers use
gets().
Schildt is probably the primary reason that so many C programmers think
exit(1) is portable.
Schildt is probably the primary reason that so many C programmers don't
understand ISO namespace.


To select a typical example of his handiwork more or less at random,
p550 of "C - The Complete Reference" 2nd edition has the following code:

void enter(void)
{
  char s[256], *p;

  do {
    printf("enter appointment %d: ", spos+1);
    gets(s);
    if(*s==0) break; /* no entry */
    p = malloc(strlen(s));
    if(!p) {
      printf("out of memory.\n");
      return;
    }
    strcpy(p, s);
    if(*s) qstore(p);
  } while(*s);
}

Now, structured it ain't, but let's not worry too much about that, when
there's so much else to worry about.

Bug 1: no guarantee that the prompt will be displayed before the input
function is called.
Bug 2: use of gets(). Anyone caring to type in 256 non-'\0' characters
can cause this program to break.
Bug 3: the malloc call is getting one byte too few to store the string,
so the strcpy will cause undefined behaviour.
Bug 4: unnecessary test of *s before qstore call.
Bug 5: unnecessary test of *s in while loop.

5 bugs in 17 lines (including whitespace and curly braces). One bug
every 3.4 lines, in a book which, despite its name, intends to be a
tutorial. Admittedly it's a small sample. Nevertheless, I once made the
mistake of claiming, in comp.lang.c, that there was bound to be at least
one page in the book that didn't have a single mistake on it anywhere,
and Dann Corbit challenged me to produce such a page. I couldn't.


-- 
Richard Heathfield
"Usenet is a strange place." - Dennis M Ritchie, 29 July 1999.
C FAQ: http://www.eskimo.com/~scs/C-faq/top.html
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