Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c++ > #86393

Re: What is the good of new way of coding?

From Bonita Montero <Bonita.Montero@gmail.com>
Newsgroups comp.lang.c++
Subject Re: What is the good of new way of coding?
Date 2022-09-17 18:34 +0200
Organization A noiseless patient Spider
Message-ID <tg4sug$6vcn$1@dont-email.me> (permalink)
References (2 earlier) <tg4mrn$75v$1@gioia.aioe.org> <tg4p7j$6kku$1@dont-email.me> <tg4qtf$1ub0$1@gioia.aioe.org> <tg4r45$6q5f$1@dont-email.me> <tg4rnu$aeq$1@gioia.aioe.org>

Show all headers | View raw

Am 17.09.2022 um 18:13 schrieb Muttley@dastardlyhq.com:
> On Sat, 17 Sep 2022 18:03:37 +0200
> Bonita Montero <Bonita.Montero@gmail.com> wrote:
>> Am 17.09.2022 um 17:59 schrieb Muttley@dastardlyhq.com:
>>> On Sat, 17 Sep 2022 17:31:19 +0200
>>> Bonita Montero <Bonita.Montero@gmail.com> wrote:
>>>> Am 17.09.2022 um 16:50 schrieb Muttley@dastardlyhq.com:
>>>>> On Sat, 17 Sep 2022 15:03:25 +0200
>>>>> Bonita Montero <Bonita.Montero@gmail.com> wrote:
>>>>>> Am 17.09.2022 um 14:46 schrieb wij:
>>>>>>> I did not update my C++ understanding (probable since C++11) to find out
>> I
>>>>>>> cannot understand what the codes are about !!!
>>>>>>>
>>>>>>> --- frorm https://groups.google.com/g/comp.lang.c++/c/2ebc6ifoPr4
>>>>>>> #include <iostream>
>>>>>>> #include <utility>
>>>>>>>
>>>>>>> using namespace std;
>>>>>>>
>>>>>>> int main()
>>>>>>> {
>>>>>>> auto pow = []<unsigned P>( double b, integral_constant<unsigned, P> )
>>>>>>> -> double
>>>>>>> {
>>>>>>> auto unroll = [&]<size_t ... Indices>( index_sequence<Indices ...> )
>>>>>>> -> double
>>>>>>> {
>>>>>>> return ((Indices, b) * ...);
>>>>>>> };
>>>>>>> if constexpr( P )
>>>>>>> return unroll( make_index_sequence<P>() );
>>>>>>> else
>>>>>>> return b;
>>>>>>> };
>>>>>>> cout << pow( 2.0, integral_constant<unsigned, 10'000>() ) << endl;
>>>>>>> }
>>>>>>> ------
>>>>>>>
>>>>>>> Question1: What would the code look like if using C++2006 for the above
>>>>>> 'program'?
>>>>>>
>>>>>> It's not possible to write that before C++20.
>>>>>
>>>>> Really? So it outputs some special assembler reserved for C++20 does it?
>>>>>
>>>>
>>>> No, you can't unroll variable.
>>>
>>> I'm pretty sure the same functionality could be achieved in older C++ or
>>> even C albeit with more lines of code.
>>>
>>
>> Show me.
>>
> 
> I don't have a c++ 20 compiler so I can't see what it does and I have better
> things to do on a saturday than run it in my head.
> 

Without C++20 you would have to unroll the fold expressions
N times, in this case 10.000 times. Have fun !

Back to comp.lang.c++ | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

What is the good of new way of coding? wij <wyniijj2@gmail.com> - 2022-09-17 05:46 -0700
  Re: What is the good of new way of coding? Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-17 15:03 +0200
    Re: What is the good of new way of coding? Muttley@dastardlyhq.com - 2022-09-17 14:50 +0000
      Re: What is the good of new way of coding? Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-17 17:31 +0200
        Re: What is the good of new way of coding? Muttley@dastardlyhq.com - 2022-09-17 15:59 +0000
          Re: What is the good of new way of coding? Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-17 18:03 +0200
            Re: What is the good of new way of coding? Muttley@dastardlyhq.com - 2022-09-17 16:13 +0000
              Re: What is the good of new way of coding? Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-17 18:34 +0200
                Re: What is the good of new way of coding? "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-09-17 19:55 +0200
                Re: What is the good of new way of coding? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-09-17 12:03 -0700
                Re: What is the good of new way of coding? Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-18 16:21 +0200
                Re: What is the good of new way of coding? Muttley@dastardlyhq.com - 2022-09-19 08:30 +0000
                Re: What is the good of new way of coding? Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-19 10:37 +0200
                Re: What is the good of new way of coding? Muttley@dastardlyhq.com - 2022-09-19 08:54 +0000
                Re: What is the good of new way of coding? Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-19 11:13 +0200
  Re: What is the good of new way of coding? Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-17 15:23 +0200
    Re: What is the good of new way of coding? Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-17 15:38 +0200
  Re: What is the good of new way of coding? Andreas Kempe <kempe@lysator.liu.se> - 2022-09-17 14:37 +0000
    Re: What is the good of new way of coding? Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-17 16:40 +0200
      Re: What is the good of new way of coding? Andreas Kempe <kempe@lysator.liu.se> - 2022-09-17 20:52 +0000
        Re: What is the good of new way of coding? Mr Flibble <flibble@reddwarf.jmc.corp> - 2022-09-17 22:18 +0100
          Re: What is the good of new way of coding? Mr Flibble <flibble@reddwarf.jmc.corp> - 2022-09-17 22:21 +0100
            Re: What is the good of new way of coding? Andreas Kempe <kempe@lysator.liu.se> - 2022-09-17 21:31 +0000
  Re: What is the good of new way of coding? Muttley@dastardlyhq.com - 2022-09-17 14:52 +0000
    Re: What is the good of new way of coding? Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-17 17:32 +0200

csiph-web