NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/lang/c-part1/1408

Internet Message Format | 1996-08-05 | 4.6 KB

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From: The Last Raptor <[e-mail]>
Newsgroups: comp.lang.c
Subject: Re: Two strange C problems.
Date: Sat, 13 Jan 1996 12:52:20 -0600
Organization: J.C. Technical Services
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Martin Ambuhl wrote:
>
> [e-mail] (Gregary John Boyles )
> in <4cojb2$[e-mail]> wrote:
>
> > I have two C problems.
>
> And what are they?  You have problems, all right.  Are they C problems?
> Maybe, but there is no way to tell when your code is all dos-isms.  Just
> to compile this junk required me to add the following at the beginning.
> If it doesn't look like it does what you expect, no big deal.  Your
> non-standard functions, structs, and macros can be defined any way one
> wants, as long as there are no syntax problems as a result.  The
> semantics are completely undefined.
>
> /* BEGINNING prologue */
> #include <stdio.h>
> typedef struct {
>     short screenheight, screenwidth;
> }   text_info;
> typedef struct { /* warning: no members */
> }  *nodetypeptr;
>
> #define initialize(x)
> #define cputs   puts
> #define cprintf   printf
> #define maxstring BUFSIZ
> #define removelineends(x,y)
> #define add(x,y,z)
> #define gettextinfo(x)
> #define getcolors(a,b,c,d)
> #define _setcursortype(x)
> #define clrscr()
> #define textcolor(x)
> #define textbackground(x)
> #define gotoxy(x,y)
> #define writescreenfull(a,b,c,d,e,f,g);
> #define setpos(x,y)
> #define displayhelp(x,y,z)
> #define readstring(a,b,c,d,e)
> #define searchstring()
> #define empty(x)    0
> #define remove(y)               /* note: remove is a reserved
>                                  * identifier (see stdio) */
> #define getch() getchar()
> #define window(a,b,c,d)
>
> char line[maxstring], bottomline[maxstring];
> enum {
>     LIGHTGRAY, BLACK, _NOCURSOR, _NORMCURSOR, space, escape, up, down,
>     pageup, pagedown, left, right, end_, home, search, help, nul
> }; /* note: _Nxxx are reserved identifiers */
>
> /* END prologue */
>
> [snip - line after line of M$dog-isms]
>
> >This program should exit such that the screen is clear with the DOS
> >prompt in the upper left corner, ...
>
> Why should it?  C doesn't even have such a concept as "screen".  If
> your implementation provides such functions, learn to use them or call
> their technical support, or pay someone to debug your crap.
>
> >..., but no, it exits with a short line
> >of text on the first line and then the DOS prompt on the next
> >line.I never(or rarely) have these sort of problems with Pascal so
> >why do they continuously crop up with C.
>
> Your problems have NOTHING to do with C.  If you can't tell the
> difference, then go back to whatever you have confused with Pascal.
>
> >
> >
> > PROBLEM 2 :
> >
> > const escape=27; const cr=13; const bs=8;
> >
> > while (ch!=cr) { . . . }
> >
> > while (ch!=escape) { . . . }
> >
> > If I replace the 27 with \27' or the 13 with '\13' then these loops
> > don't work i.e. an infinite loop results. WHY?
>
> Clever.  You have worked out that octal and decimal are not the same.
> Just a hint:
> \13 == 11
> \15 == 13
> \27 == 23
> \33 == 27
>
>
> > Also if I want to do somthing like this : puts("\24 \25"); which
> > should print the up and down arrows on the screen (ASCII 24 and
> > 25), but no, it prints some other ASCII characters. As far as I can
> > tell C has its own unique character table, at least for the control
> > characters. WHY?
>
> The IBM-extended character set (_not_ ASCII) defines the Up arrow and
> Down arrow as \30 == 24 and \31 == 25 (\24 == 20 is a paragraph sign.
> \25 == 21 is a section sign).  This has nothing to do with C (except for
> the use of \ooo for octal chars), and nothing to do with ASCII.  The
> world is not defined by your PC-toy.
>
> > Sometimes I wonder whether some one needs to go back an rewrite the
> > damn language so that it works sensibly and predictably like Pascal
> > can be relied upon to do.
>
> Learning how to read would be a hell of a lot more useful.  The only
> thing here which does not work sensibly and predictably is your brain.
>
>
> --
> * Martin Ambuhl       net: [e-mail]
> * Chicago, IL (USA)That was so nice of you Martin........
Try a little patince next time or do you prefer being an ahole.
--
J.C. Technical Services                 The Last Raptor
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