Re: why use static_cast ?

From	Manfred <noname@add.invalid>
Newsgroups	comp.lang.c++
Subject	Re: why use static_cast ?
Date	2022-10-23 20:27 +0200
Organization	Aioe.org NNTP Server
Message-ID	<tj413d$1ca4$1@gioia.aioe.org> (permalink)
References	(5 earlier) <one4L.632092$Ny99.208808@fx16.iad> <tirvme$bklh$4@dont-email.me> <tiuqi5$mhjd$1@dont-email.me> <tj0063$rtfp$1@dont-email.me> <tj1ib1$jk7$1@gioia.aioe.org>

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On 10/22/2022 10:03 PM, Lynn McGuire wrote:
> On 10/22/2022 12:47 AM, JiiPee wrote:
>> On 21/10/2022 22:05, Lynn McGuire wrote:
>>> I am always concerned about speed.
>>
>> Me also if needed. But... for example in a user interface programming 
>> speed it not important. I mean, when opening a dialog box takes 0.0001 
>> seconds or 0.0002 seconds makes no difference :). And I am mostly 
>> doing this kind of programming, when small things are processed.
> 
> I am porting a 700,000 line Fortran 77 + 50,000 line C++ engineering 
> software application to pure C++.

This sounds even more as a reason to get to very stable C++ in the 
process. I'd not want to have any chance of obscure UB hidden deeply in 
the result code.

Which begs the question from the original post:

>    longint nfac [8];
>    fem::str <8> * nfac_str = (fem::str <8> *) nfac;
> 
> fem::str <8> is an 8 character object that acts like a Fortran character*8.  longint is a long long.

Is the cast to/from 8 char string and long long really the best you want 
here?
Unless I am missing something, if you want e.g. to compare those 
strings, I'd expect that in any decent implementation memcmp is 
optimized just fine.

   I am trying to not lose any speed in
> the process.

Sure, but correctness always comes first.

> 
> Thanks,
> Lynn

Thread

why use static_cast ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-10-19 21:01 -0500
  Re: why use static_cast ? "daniel...@gmail.com" <danielaparker@gmail.com> - 2022-10-19 19:40 -0700
    Re: why use static_cast ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-10-20 00:21 -0500
      Re: why use static_cast ? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-10-19 23:21 -0700
        Re: why use static_cast ? Juha Nieminen <nospam@thanks.invalid> - 2022-10-20 07:19 +0000
          Re: why use static_cast ? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-10-20 00:21 -0700
      Re: why use static_cast ? Paul N <gw7rib@aol.com> - 2022-10-20 04:23 -0700
        Re: why use static_cast ? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-10-20 14:14 +0100
        Re: why use static_cast ? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-10-20 09:17 -0700
          Re: why use static_cast ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-10-20 09:52 -0700
            Re: why use static_cast ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-15 17:10 -0800
              Re: why use static_cast ? Juha Nieminen <nospam@thanks.invalid> - 2022-11-16 09:26 +0000
                Re: why use static_cast ? David Brown <david.brown@hesbynett.no> - 2022-11-16 14:36 +0100
                Re: why use static_cast ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-20 05:54 -0800
      Re: why use static_cast ? "daniel...@gmail.com" <danielaparker@gmail.com> - 2022-10-20 08:11 -0700
  Re: why use static_cast ? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-10-19 20:09 -0700
  Re: why use static_cast ? Juha Nieminen <nospam@thanks.invalid> - 2022-10-20 05:44 +0000
    Re: why use static_cast ? Gawr Gura <gawrgura@mail.hololive.com> - 2022-10-20 14:50 +0000
      Re: why use static_cast ? JiiPee <kerrttuPoistaTama11@gmail.com> - 2022-10-20 17:53 +0300
  Re: why use static_cast ? Bonita Montero <Bonita.Montero@gmail.com> - 2022-10-20 08:52 +0200
    Re: why use static_cast ? JiiPee <kerrttuPoistaTama11@gmail.com> - 2022-10-20 17:52 +0300
  Re: why use static_cast ? scott@slp53.sl.home (Scott Lurndal) - 2022-10-20 13:55 +0000
    Re: why use static_cast ? JiiPee <kerrttuPoistaTama11@gmail.com> - 2022-10-20 17:55 +0300
      Re: why use static_cast ? scott@slp53.sl.home (Scott Lurndal) - 2022-10-20 15:01 +0000
        Re: why use static_cast ? JiiPee <kerrttuPoistaTama11@gmail.com> - 2022-10-20 18:32 +0300
          Re: why use static_cast ? scott@slp53.sl.home (Scott Lurndal) - 2022-10-20 16:07 +0000
            Re: why use static_cast ? JiiPee <kerrttuPoistaTama11@gmail.com> - 2022-10-20 20:14 +0300
              Re: why use static_cast ? scott@slp53.sl.home (Scott Lurndal) - 2022-10-20 17:30 +0000
                Re: why use static_cast ? JiiPee <kerrttuPoistaTama11@gmail.com> - 2022-10-20 20:41 +0300
              Re: why use static_cast ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-10-21 14:05 -0500
                Re: why use static_cast ? JiiPee <kerrttuPoistaTama11@gmail.com> - 2022-10-22 00:09 +0300
                Re: why use static_cast ? JiiPee <kerrttuPoistaTama11@gmail.com> - 2022-10-22 08:47 +0300
                Re: why use static_cast ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-10-22 15:03 -0500
                Re: why use static_cast ? Muttley@dastardlyhq.com - 2022-10-23 07:35 +0000
                Re: why use static_cast ? JiiPee <kerrttuPoistaTama11@gmail.com> - 2022-10-23 15:28 +0300
                Re: why use static_cast ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-10-23 14:13 -0500
                Re: why use static_cast ? Manfred <noname@add.invalid> - 2022-10-23 20:27 +0200
                Re: why use static_cast ? Michael S <already5chosen@yahoo.com> - 2022-10-23 15:04 -0700
                Re: why use static_cast ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-10-23 23:14 -0500
          Re: why use static_cast ? Bonita Montero <Bonita.Montero@gmail.com> - 2022-10-21 17:21 +0200
      Re: why use static_cast ? Bonita Montero <Bonita.Montero@gmail.com> - 2022-10-21 17:24 +0200
    Re: why use static_cast ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-10-20 13:21 -0500
      Re: why use static_cast ? Manfred <noname@add.invalid> - 2022-10-21 05:52 +0200
        Re: why use static_cast ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-10-21 13:59 -0500
          Re: why use static_cast ? Bo Persson <bo@bo-persson.se> - 2022-10-22 18:31 +0200
            Re: why use static_cast ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-10-22 15:05 -0500
            Re: why use static_cast ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-10-22 17:34 -0500
        Re: why use static_cast ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-02 17:54 -0700
          Re: why use static_cast ? Öö Tiib <ootiib@hot.ee> - 2022-11-03 08:51 -0700
            Re: why use static_cast ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-15 16:19 -0800
              Re: why use static_cast ? Öö Tiib <ootiib@hot.ee> - 2022-11-15 23:02 -0800
                Re: why use static_cast ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-20 05:59 -0800
                Re: why use static_cast ? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-11-20 15:05 +0100
                Re: why use static_cast ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-11-20 07:22 -0800
                Re: why use static_cast ? Öö Tiib <ootiib@hot.ee> - 2022-11-20 08:40 -0800
                Re: why use static_cast ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-12-28 20:43 -0800
    Re: why use static_cast ? Juha Nieminen <nospam@thanks.invalid> - 2022-11-04 07:27 +0000
      Re: why use static_cast ? scott@slp53.sl.home (Scott Lurndal) - 2022-11-04 13:47 +0000
        Re: why use static_cast ? Vir Campestris <vir.campestris@invalid.invalid> - 2022-11-05 21:34 +0000
        Re: why use static_cast ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2022-11-06 03:25 -0500
        Re: why use static_cast ? Paavo Helde <eesnimi@osa.pri.ee> - 2022-11-06 17:34 +0200
          Re: why use static_cast ? Juha Nieminen <nospam@thanks.invalid> - 2022-11-07 07:13 +0000
      Re: why use static_cast ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-11-04 09:09 -0700
  Re: why use static_cast ? Lynn McGuire <lynnmcguire5@gmail.com> - 2022-10-20 13:21 -0500

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