validity of ... reasons for preferring C over C++

From	Nobody <nobody@nowhere.invalid>
Newsgroups	comp.arch.embedded
Subject	validity of ... reasons for preferring C over C++
Date	2014-10-17 00:00 +0100
Organization	A noiseless patient Spider
Message-ID	<pan.2014.10.16.23.00.30.486000@nowhere.invalid> (permalink)

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On Wed, 15 Oct 2014 19:21:11 +0200, Wouter van Ooijen wrote:

> PS I am (in the context of this question) NOT interested in

> - whether a reason is valid (please start a different thread for 
> discussing this, I'll surely join in).

Okay, then.

To start with some comments from the original post:

> - semantic distance to the machine code (I can't easily see what code 
> this C++ construct will cause)

If you think you know what code a given C construct will generate, you've
been out of the loop too long.

Modern C compilers can be very aggressive when it comes to optimisation,
taking full advantage of the concept of "undefined behaviour", including
what used to be obscure cases such as aliasing.

If you need the kind of control you get from assembler, you either need to
use assembler, or at least look at the actual assembler code the compiler
is generating. If you think you know, think again.

> - C++ stronger typing gets in the way (forces you to write lots of casts)

This is an advantage, not a disadvantage.

If you're targeting a specific CPU, you don't need to worry about one
of the reasons why casts are problematic: the fact that the standard
doesn't actually define representation. You can ignore the fact that ...

Integers may be big-endian, little-endian, Vax-endian or something else;
signed integers may use twos-complement, ones-complement, or sign-bit
representation; floats could be just about anything; structures may have
padding anywhere other than before the first element; pointers may be
simple indices into a flat address space or complex structures involving
tags, segments and/or whatever else.

You do, however, still need to consider the effects of the cast with
respect to C's aliasing rules. The compiler is entitled to assume (with
some caveats) that objects with different types do not overlap; modifying
one will not affect the other. But casts tend to result in exactly that.

And the "entitled to assume" isn't just for language lawyers any more;
modern compilers (at least the ones for desktop/server architectures,
which are enveloping an increasing proportion of the "embedded" space) do
actually take advantage of that freedom.

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validity of ... reasons for preferring C over C++ Nobody <nobody@nowhere.invalid> - 2014-10-17 00:00 +0100
  Re: validity of ... reasons for preferring C over C++ Wouter van Ooijen <wouter@voti.nl> - 2014-10-17 07:38 +0200
  Re: validity of ... reasons for preferring C over C++ David Brown <david.brown@hesbynett.no> - 2014-10-17 09:27 +0200
    Re: validity of ... reasons for preferring C over C++ Tom Gardner <spamjunk@blueyonder.co.uk> - 2014-10-17 09:29 +0100
      Re: validity of ... reasons for preferring C over C++ David Brown <david.brown@hesbynett.no> - 2014-10-17 11:19 +0200
        Re: validity of ... reasons for preferring C over C++ Paul Rubin <no.email@nospam.invalid> - 2014-10-17 02:35 -0700
          Re: validity of ... reasons for preferring C over C++ Arlet Ottens <usenet+5@c-scape.nl> - 2014-10-17 11:43 +0200
            Re: validity of ... reasons for preferring C over C++ Tom Gardner <spamjunk@blueyonder.co.uk> - 2014-10-17 12:12 +0100
              Re: validity of ... reasons for preferring C over C++ Arlet Ottens <usenet+5@c-scape.nl> - 2014-10-17 13:25 +0200
                Re: validity of ... reasons for preferring C over C++ Tom Gardner <spamjunk@blueyonder.co.uk> - 2014-10-17 12:40 +0100
            Re: validity of ... reasons for preferring C over C++ Niklas Holsti <niklas.holsti@tidorum.invalid> - 2014-10-17 20:12 +0300
              Re: validity of ... reasons for preferring C over C++ Rob Gaddi <rgaddi@technologyhighland.invalid> - 2014-10-17 10:18 -0700
                Re: validity of ... reasons for preferring C over C++ upsidedown@downunder.com - 2014-10-17 21:53 +0300
                Re: validity of ... reasons for preferring C over C++ Niklas Holsti <niklas.holsti@tidorum.invalid> - 2014-10-17 22:59 +0300
                Re: validity of ... reasons for preferring C over C++ Paul Rubin <no.email@nospam.invalid> - 2014-10-17 13:23 -0700
                Re: validity of ... reasons for preferring C over C++ Jacob Sparre Andersen <jacob@jacob-sparre.dk> - 2014-10-18 17:46 +0200
                Re: validity of ... reasons for preferring C over C++ Paul Rubin <no.email@nospam.invalid> - 2014-10-18 11:45 -0700
                Re: validity of ... reasons for preferring C over C++ Niklas Holsti <niklas.holsti@tidorum.invalid> - 2014-10-19 01:51 +0300
                Re: validity of ... reasons for preferring C over C++ Jacob Sparre Andersen <jacob@jacob-sparre.dk> - 2014-10-19 12:43 +0200
                Re: validity of ... reasons for preferring C over C++ Jacob Sparre Andersen <jacob@jacob-sparre.dk> - 2014-10-18 17:44 +0200
          Re: validity of ... reasons for preferring C over C++ David Brown <david.brown@hesbynett.no> - 2014-10-17 12:44 +0200
            Re: validity of ... reasons for preferring C over C++ Tom Gardner <spamjunk@blueyonder.co.uk> - 2014-10-17 12:13 +0100
            Re: validity of ... reasons for preferring C over C++ Niklas Holsti <niklas.holsti@tidorum.invalid> - 2014-10-17 20:15 +0300
              Re: validity of ... reasons for preferring C over C++ Arlet Ottens <usenet+5@c-scape.nl> - 2014-10-17 19:18 +0200
              Re: validity of ... reasons for preferring C over C++ David Brown <david.brown@hesbynett.no> - 2014-10-17 23:03 +0200
                Re: validity of ... reasons for preferring C over C++ Paul Rubin <no.email@nospam.invalid> - 2014-10-17 14:11 -0700
                Re: validity of ... reasons for preferring C over C++ David Brown <david.brown@hesbynett.no> - 2014-10-18 20:14 +0200
                Re: validity of ... reasons for preferring C over C++ Tom Gardner <spamjunk@blueyonder.co.uk> - 2014-10-18 22:15 +0100
                Re: validity of ... reasons for preferring C over C++ glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-10-18 23:07 +0000
                Re: validity of ... reasons for preferring C over C++ Tom Gardner <spamjunk@blueyonder.co.uk> - 2014-10-19 00:36 +0100
                Re: validity of ... reasons for preferring C over C++ Niklas Holsti <niklas.holsti@tidorum.invalid> - 2014-10-19 10:55 +0300
                Re: validity of ... reasons for preferring C over C++ Tom Gardner <spamjunk@blueyonder.co.uk> - 2014-10-19 09:33 +0100
                Re: validity of ... reasons for preferring C over C++ "Boudewijn Dijkstra" <sp4mtr4p.boudewijn@indes.com> - 2014-10-20 15:04 +0200
                Re: validity of ... reasons for preferring C over C++ David Brown <david.brown@hesbynett.no> - 2014-10-19 13:32 +0200
                Re: validity of ... reasons for preferring C over C++ Wouter van Ooijen <wouter@voti.nl> - 2014-10-17 23:44 +0200
                Re: validity of ... reasons for preferring C over C++ David Brown <david.brown@hesbynett.no> - 2014-10-18 20:10 +0200
                Re: validity of ... reasons for preferring C over C++ Niklas Holsti <niklas.holsti@tidorum.invalid> - 2014-10-18 23:38 +0300
                Re: validity of ... reasons for preferring C over C++ Tom Gardner <spamjunk@blueyonder.co.uk> - 2014-10-18 22:21 +0100
                Re: validity of ... reasons for preferring C over C++ Niklas Holsti <niklas.holsti@tidorum.invalid> - 2014-10-19 10:43 +0300
                Re: validity of ... reasons for preferring C over C++ Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> - 2014-10-19 09:38 +0000
                Re: validity of ... reasons for preferring C over C++ David Brown <david.brown@hesbynett.no> - 2014-10-19 14:07 +0200
                Re: validity of ... reasons for preferring C over C++ Paul Rubin <no.email@nospam.invalid> - 2014-10-19 19:47 -0700
                Re: validity of ... reasons for preferring C over C++ Niklas Holsti <niklas.holsti@tidorum.invalid> - 2014-10-20 06:55 +0300
                Re: validity of ... reasons for preferring C over C++ Paul Rubin <no.email@nospam.invalid> - 2014-10-19 21:02 -0700
                Re: validity of ... reasons for preferring C over C++ britt.snodgrass@gmail.com - 2014-10-20 04:02 -0700
                Re: validity of ... reasons for preferring C over C++ Niklas Holsti <niklas.holsti@tidorum.invalid> - 2014-10-20 18:51 +0300
                C and Ada, was: Re: validity of ... reasons for preferring C over C++ Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> - 2014-10-21 00:30 +0000
                Re: C and Ada, was: Re: validity of ... reasons for preferring C over C++ Les Cargill <lcargill99@comcast.com> - 2014-10-20 20:49 -0500
                Re: C and Ada, was: Re: validity of ... reasons for preferring C over C++ Jacob Sparre Andersen <jacob@jacob-sparre.dk> - 2014-10-21 09:11 +0200
                Re: C and Ada, was: Re: validity of ... reasons for preferring C over C++ Les Cargill <lcargill99@comcast.com> - 2014-10-21 08:34 -0500
                Re: validity of ... reasons for preferring C over C++ Niklas Holsti <niklas.holsti@tidorum.invalid> - 2014-10-19 21:23 +0300
                Re: validity of ... reasons for preferring C over C++ Nobody <nobody@nowhere.invalid> - 2014-10-20 03:39 +0100
          Re: validity of ... reasons for preferring C over C++ Tom Gardner <spamjunk@blueyonder.co.uk> - 2014-10-17 12:07 +0100
        Re: validity of ... reasons for preferring C over C++ Tom Gardner <spamjunk@blueyonder.co.uk> - 2014-10-17 12:06 +0100
          Re: validity of ... reasons for preferring C over C++ David Brown <david.brown@hesbynett.no> - 2014-10-17 14:12 +0200
            Re: validity of ... reasons for preferring C over C++ Tom Gardner <spamjunk@blueyonder.co.uk> - 2014-10-17 13:16 +0100
          Re: validity of ... reasons for preferring C over C++ Stef <stef33d@yahooI-N-V-A-L-I-D.com.invalid> - 2014-10-17 14:13 +0200
            Re: validity of ... reasons for preferring C over C++ Arlet Ottens <usenet+5@c-scape.nl> - 2014-10-17 14:35 +0200
              Re: validity of ... reasons for preferring C over C++ Tom Gardner <spamjunk@blueyonder.co.uk> - 2014-10-17 13:59 +0100
            Re: validity of ... reasons for preferring C over C++ Wouter van Ooijen <wouter@voti.nl> - 2014-10-17 17:06 +0200
            Re: validity of ... reasons for preferring C over C++ upsidedown@downunder.com - 2014-10-17 19:41 +0300
      Re: validity of ... reasons for preferring C over C++ Clifford Heath <no.spam@please.net> - 2014-10-18 10:14 +1100
        Re: validity of ... reasons for preferring C over C++ Tom Gardner <spamjunk@blueyonder.co.uk> - 2014-10-18 00:36 +0100
          Re: validity of ... reasons for preferring C over C++ Clifford Heath <no.spam@please.net> - 2014-10-20 09:45 +1100
        Re: validity of ... reasons for preferring C over C++ Niklas Holsti <niklas.holsti@tidorum.invalid> - 2014-10-18 08:52 +0300
          Re: validity of ... reasons for preferring C over C++ Tom Gardner <spamjunk@blueyonder.co.uk> - 2014-10-18 09:41 +0100
  Re: validity of ... reasons for preferring C over C++ Dave Nadler <drn@nadler.com> - 2014-10-20 09:46 -0700
    Re: validity of ... reasons for preferring C over C++ Paul Rubin <no.email@nospam.invalid> - 2014-10-20 16:26 -0700
      Re: validity of ... reasons for preferring C over C++ Dave Nadler <drn@nadler.com> - 2014-10-20 16:42 -0700
        Re: validity of ... reasons for preferring C over C++ Paul Rubin <no.email@nospam.invalid> - 2014-10-20 17:24 -0700
          Re: validity of ... reasons for preferring C over C++ John Devereux <john@devereux.me.uk> - 2014-10-21 19:09 +0100
            Re: validity of ... reasons for preferring C over C++ Wouter van Ooijen <wouter@voti.nl> - 2014-10-24 16:38 +0200
          Re: validity of ... reasons for preferring C over C++ Dave Nadler <drn@nadler.com> - 2014-10-21 15:12 -0700
            Re: validity of ... reasons for preferring C over C++ Paul Rubin <no.email@nospam.invalid> - 2014-10-21 16:39 -0700
              Re: validity of ... reasons for preferring C over C++ Nobody <nobody@nowhere.invalid> - 2014-10-22 01:43 +0100
              Re: validity of ... reasons for preferring C over C++ Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2014-10-22 20:00 +0200
          Re: validity of ... reasons for preferring C over C++ Stefan Reuther <stefan.news@arcor.de> - 2014-10-22 18:49 +0200
      Re: validity of ... reasons for preferring C over C++ Dave Nadler <drn@nadler.com> - 2014-10-21 15:15 -0700
      Re: validity of ... reasons for preferring C over C++ Dave Nadler <drn@nadler.com> - 2014-10-22 04:45 -0700
        Re: validity of ... reasons for preferring C over C++ Paul Rubin <no.email@nospam.invalid> - 2014-10-22 09:30 -0700
          Re: validity of ... reasons for preferring C over C++ Dave Nadler <drn@nadler.com> - 2014-10-23 12:25 -0700
            Re: validity of ... reasons for preferring C over C++ Paul Rubin <no.email@nospam.invalid> - 2014-10-23 15:17 -0700
              Re: validity of ... reasons for preferring C over C++ glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-10-23 22:59 +0000
                Re: validity of ... reasons for preferring C over C++ Paul Rubin <no.email@nospam.invalid> - 2014-10-23 16:02 -0700
              Re: validity of ... reasons for preferring C over C++ Dave Nadler <drn@nadler.com> - 2014-10-27 08:30 -0700
                Re: validity of ... reasons for preferring C over C++ Paul Rubin <no.email@nospam.invalid> - 2014-10-27 09:00 -0700
                Re: validity of ... reasons for preferring C over C++ Dave Nadler <drn@nadler.com> - 2014-10-27 09:24 -0700
                Re: validity of ... reasons for preferring C over C++ Paul Rubin <no.email@nospam.invalid> - 2014-10-27 09:30 -0700
                Re: validity of ... reasons for preferring C over C++ glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-10-28 00:52 +0000
              Re: validity of ... reasons for preferring C over C++ David Brown <david.brown@hesbynett.no> - 2014-10-28 08:45 +0100
                Re: validity of ... reasons for preferring C over C++ Paul Rubin <no.email@nospam.invalid> - 2014-10-28 02:00 -0700
                Re: validity of ... reasons for preferring C over C++ George Neuner <gneuner2@comcast.net> - 2014-10-30 11:56 -0400
                Re: validity of ... reasons for preferring C over C++ upsidedown@downunder.com - 2014-10-28 19:59 +0200
                Re: validity of ... reasons for preferring C over C++ David Brown <david.brown@hesbynett.no> - 2014-10-28 23:46 +0100
                Re: validity of ... reasons for preferring C over C++ upsidedown@downunder.com - 2014-10-29 07:27 +0200
                Re: validity of ... reasons for preferring C over C++ David Brown <david.brown@hesbynett.no> - 2014-10-29 10:11 +0100
                Re: validity of ... reasons for preferring C over C++ Robert Wessel <robertwessel2@yahoo.com> - 2014-10-29 10:21 -0500
                Re: validity of ... reasons for preferring C over C++ glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-10-29 20:15 +0000
                Re: validity of ... reasons for preferring C over C++ Robert Wessel <robertwessel2@yahoo.com> - 2014-10-30 11:33 -0500
                Re: validity of ... reasons for preferring C over C++ glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-10-30 19:07 +0000
                Re: validity of ... reasons for preferring C over C++ Robert Wessel <robertwessel2@yahoo.com> - 2014-10-30 16:19 -0500
                Re: validity of ... reasons for preferring C over C++ Nobody <nobody@nowhere.invalid> - 2014-10-31 07:32 +0000
                Re: validity of ... reasons for preferring C over C++ glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-10-31 08:45 +0000
                Re: validity of ... reasons for preferring C over C++ Reinhardt Behm <rbehm@hushmail.com> - 2014-10-31 18:15 +0800
                Re: validity of ... reasons for preferring C over C++ glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-10-31 22:03 +0000
                Re: validity of ... reasons for preferring C over C++ Robert Wessel <robertwessel2@yahoo.com> - 2014-10-31 09:53 -0500
                Re: validity of ... reasons for preferring C over C++ glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2014-10-31 22:17 +0000
                Re: validity of ... reasons for preferring C over C++ Les Cargill <lcargill99@comcast.com> - 2014-10-31 17:50 -0500
            Re: validity of ... reasons for preferring C over C++ Nobody <nobody@nowhere.invalid> - 2014-10-28 04:37 +0000
    Re: validity of ... reasons for preferring C over C++ Stefan Reuther <stefan.news@arcor.de> - 2014-10-21 19:12 +0200
      Re: validity of ... reasons for preferring C over C++ Dave Nadler <drn@nadler.com> - 2014-10-21 15:06 -0700
        Re: validity of ... reasons for preferring C over C++ Stefan Reuther <stefan.news@arcor.de> - 2014-10-22 19:06 +0200

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