From: hebert@prism.uvsq.fr (Renaud HEBERT)
Subject: Re: "Subtract C, add Ada"
Date: 20 Jan 1995 13:22:17 GMT
Date: 1995-01-20T13:22:17+00:00 [thread overview]
Message-ID: <3fode9$dap@soleil.uvsq.fr> (raw)
In-Reply-To: 3fo2ot$su2@miranda.gmrc.gecm.com
In article <3fo2ot$su2@miranda.gmrc.gecm.com>, bill@valiant (R.A.L Williams) writes:
|>
|> In article <3f5s92$3id@info.epfl.ch> you wrote:
|> : In article <3f4mbe$rud@cronkite.seas.gwu.edu>, dobrien@seas.gwu.edu (David O'Brien) writes:
|> : |> R.A.L Williams (bill@valiant) wrote:
|> : |> : My experience of writing software and running software projects in C
|> : |> : highlights four common low-level C errors:
|> : |> : 1. = instead of == and vice versa
|> : |>
|> : |> I have to wonder. What if C defined the logical equals operator to be
|> : |> "=" and the assignment operator to be ":=" just like Ada, Algol, Pascal,
|> : |> Modula-x, etc? Would this error still exist???
|>
|> : The problem is in the language definition, not in the choic of symbols.
|> : C is one of the rare language I use to allow having an assignment after
|> : the if statement. All other languages only allow for a boolean test.
|>
|> : I never saw a good reason for allowing this.
|>
|> I think there are three reasons:
|> 1. It allows your code to be more compact. Many people think this is
|> a disadvantage, and so it is if the code will be read by comparative
|> novices, but it can improve readability to C experts who are
|> expecting such tricks.
|>
|> NB DONT confuse compactness with poor layout! I find that, for example:
|>
|> while ((c = getchar()) == ' ')
|> {
|> /* count spaces */
|> }
|>
|> is clearer than the 'expanded' alternative (to *me* :-).
|>
|> 2. All expressions in C have a value. Conditional tests succeed on
|> non-zero and fail on zero. Therefore, to maintain orthogonality,
|> as far as possible, there is no reason to exclude an assignment
|> expression from a condition.
|>
|> 3. Finally, I suspect, this can simplify the optimisation algorithms
|> in the compiler.
|>
|> Personally, the lack of this sort of compactness in Ada, and things like
|> pre- and post-increment/decrement are one of my minor gripes about the
|> language. OK, its no big thing to write:
|>
|> P(I) := Q(I);
|> I := I + 1;
|>
|> instead of
|>
|> *p++ = *q++;
|>
|> but I actually *do* find the C representation easier/better etc. (perhaps
|> I'm wierd?)
Even if I like C, I think that this ++ is ugly and I'm glad that there isn't such
a thing in Ada. On the other hand what do you think about the operators += *= ...
They make thing shorter AND easier to read, a += 5; means exactly add 5 to a.
So don't you think that these construct have their place in Ada.
|>
|> : --
|> : Laurent Gasser (gasser@dma.epfl.ch)
|> : Computers do not solve problems, they execute solutions.
|>
|> : I know very few ideas worth dying for, none is worth killing.
|>
|> Very true, but quite a few are worth a pint in the pub.
|>
|> Bill Williams
|>
--
Renaud HEBERT e-mail: Renaud.Hebert@prism.uvsq.fr
next prev parent reply other threads:[~1995-01-20 13:22 UTC|newest]
Thread overview: 85+ messages / expand[flat|nested] mbox.gz Atom feed top
1995-01-20 10:20 "Subtract C, add Ada" R.A.L Williams
1995-01-20 13:22 ` Renaud HEBERT [this message]
1995-01-24 3:35 ` David Moore
1995-01-25 5:38 ` Robert Dewar
1995-01-28 16:35 ` Jules
1995-01-29 8:06 ` Matt Kennel
1995-01-30 5:31 ` Michael Feldman
1995-01-31 22:22 ` David O'Brien
1995-01-24 20:23 ` N. Mellor
1995-01-25 8:50 ` Robb Nebbe
1995-01-25 14:19 ` John Volan
1995-01-26 5:07 ` Samuel Mize
1995-01-26 18:51 ` Mark A Biggar
1995-01-21 15:18 ` Robert Dewar
1995-01-21 21:03 ` David O'Brien
1995-01-23 3:09 ` Jay Martin
1995-01-23 12:50 ` Andrew McConnell
1995-01-24 0:54 ` Matt Kennel
1995-01-25 17:03 ` Norman H. Cohen
1995-01-26 1:13 ` Dr. Richard Botting
1995-01-26 14:32 ` Anders Juul Munch
1995-01-24 0:17 ` Bob Kitzberger
1995-01-23 20:46 ` Robert Firth
1995-01-24 14:25 ` Samuel Mize
1995-01-25 7:27 ` David O'Brien
1995-01-25 12:14 ` Robert A Duff
1995-01-25 5:57 ` David O'Brien
[not found] ` <3g9rf0$71k@Starbase.NeoSoft.COM>
1995-01-28 21:08 ` David O'Brien
1995-01-31 18:07 ` Samuel Mize
1995-02-01 10:23 ` Samuel Mize
1995-01-30 0:24 ` Mark S. Hathaway
1995-01-31 3:30 ` Jay Martin
1995-02-01 13:25 ` Jesper Kaagaard
-- strict thread matches above, loose matches on Subject: below --
1995-02-10 13:49 R.A.L Williams
[not found] <3gsr0e$oin@miranda.gmrc.gecm.com>
1995-02-07 16:58 ` Mark S. Hathaway
1995-02-08 7:39 ` Travis C. Porco
1995-02-08 16:07 ` Fred J. McCall
1995-02-08 21:30 ` Garlington KE
1995-01-31 9:34 R.A.L Williams
1995-02-01 16:45 ` Charles H. Sampson
1995-01-23 8:49 R.A.L Williams
1995-01-25 23:18 ` Charles H. Sampson
1995-01-20 9:33 R.A.L Williams
[not found] <3fgphd$sc3@rational.rational.com>
1995-01-20 5:51 ` RonaldS60
1995-02-07 13:55 ` Robert C. Soong
[not found] <3fdcoi$chn@miranda.gmrc.gecm.com>
1995-01-20 5:01 ` Samuel Mize
1995-01-20 22:07 ` Garlington KE
1995-01-24 5:02 ` R_Tim_Coslet
[not found] <3etund$hnr@miranda.gmrc.gecm.com>
1995-01-12 9:56 ` Erik Svensson
1995-01-12 14:44 ` Norman H. Cohen
1995-01-13 1:51 ` David O'Brien
1995-01-13 12:38 ` Laurent Gasser
1995-01-13 20:53 ` John DiCamillo
[not found] ` <3f8fnf$c8p@gamma.ois.com>
1995-01-16 11:02 ` Matt Kennel
[not found] ` <milodD2IFpG.329@netcom.com>
1995-01-17 21:39 ` R. William Beckwith
[not found] ` <3fa11q$sdh@gnat.cs.nyu.edu>
1995-01-16 20:20 ` David Moore
1995-01-14 0:24 ` David O'Brien
1995-01-20 4:43 ` Samuel Mize
1995-01-21 20:28 ` David O'Brien
1995-01-22 21:12 ` Robert Dewar
1995-01-23 18:35 ` Norman H. Cohen
1995-01-23 19:18 ` John Cosby - The Coz
1995-01-24 14:11 ` Samuel Mize
1995-01-14 10:37 ` Keith Thompson
[not found] ` <3fcjgt$b0v@cronkite.seas.gwu.edu>
1995-01-16 18:47 ` Robert Dewar
[not found] ` <D2It0r.4rp@inmet.camb.inmet.com>
1995-01-17 14:11 ` Norman H. Cohen
1994-12-30 16:06 Mitch Gart
1995-01-03 19:04 ` whiting_ms@corning.com (Matt Whiting)
1995-01-05 4:31 ` Michael Feldman
1995-01-04 21:40 ` Fred McCall
1995-01-05 4:30 ` Richard Pattis
1995-01-05 16:07 ` Kevin Weise
1995-01-06 13:06 ` Jahn Rentmeister
1995-01-06 16:47 ` Laurent Gasser
1995-01-06 17:29 ` David Weller
1995-01-06 17:30 ` David Weller
1995-01-10 18:28 ` Bob Kitzberger
1995-01-06 23:36 ` Kenneth Almquist
1995-01-04 22:45 ` Jay M. Martin
1995-01-05 4:37 ` Michael Feldman
1995-01-05 18:08 ` Jay Martin
1995-01-05 23:56 ` Robert Dewar
1995-01-08 8:04 ` Jay Martin
1995-01-06 0:07 ` Michael M. Bishop
1995-01-10 21:30 ` Jay Martin
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