220 19208 article Path: news.gmane.org!not-for-mail From: Vlad from Moscow Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Overloading std::begin and std::end for std::pair Date: Thu, 23 Jul 2015 10:57:37 -0700 (PDT) Lines: 167 Approved: news@gmane.org Message-ID: References: <012fd35d-96fd-4775-835e-2105176c4f97@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_666_974218136.1437674258041" X-Trace: ger.gmane.org 1437674262 30013 80.91.229.3 (23 Jul 2015 17:57:42 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 23 Jul 2015 17:57:42 +0000 (UTC) Cc: vlad.moscow@mail.ru To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCXLLRHD7IDRBEWWYSWQKGQEQK3HXSI@isocpp.org Thu Jul 23 19:57:42 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-vn0-f72.google.com ([209.85.216.72]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZIKkW-0000TR-AM for gclcip-std-proposals@m.gmane.org; Thu, 23 Jul 2015 19:57:40 +0200 Original-Received: by vnav141 with SMTP id v141sf134231722vna.1 for ; Thu, 23 Jul 2015 10:57:39 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:cc:message-id:in-reply-to :references:subject:mime-version:content-type:x-original-sender :reply-to:precedence:mailing-list:list-id:x-spam-checked-in-group :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=Zig8KYjxYdfvhIjLEm3bx65uRgDJg/H87MyA0iD4bWQ=; b=btwKw/Ga4M3vFg7EEqg4PMw6YIkkUTNJ1EFJocZs0MPcCjhPCNgnPmNq72JX7UVuC9 udJM2hBibgWaSGZAYlFGGpgEPSFHWNvYNli1WFC/utpBb205PVYT8aqR1kMlWcjoS+ZV unKB+TZH/LbMV8Q6DZc0k/Di4mD8yj9NajXDmH9JlZ2/vjv1cHxL+jfp15SBjyS1+57O m+aU+8kOK9PJew/Tt31d6PAN8qgGH+djpfbXqKShnYbDK/nYT7SgquRS2kg8zP42jGSM E2k8Y4mrBeVIBQVM2tkwJXu+z08E3DvrH+Gc3lyOrPCTXSvjeOMMT42xKUsGjx70ep07 aLdA== X-Gm-Message-State: ALoCoQn2uI+I1gIqAKMqtBMBUcWWKBTbJ8yO6xwo3Lcse59NRaA3APPb5cdCAW9IcBEbqYwSPNy9 X-Received: by 10.129.90.134 with SMTP id o128mr6473737ywb.14.1437674259475; Thu, 23 Jul 2015 10:57:39 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.19.105 with SMTP id 96ls1089665qgg.68.gmail; Thu, 23 Jul 2015 10:57:38 -0700 (PDT) X-Received: by 10.140.106.247 with SMTP id e110mr207385qgf.7.1437674258667; Thu, 23 Jul 2015 10:57:38 -0700 (PDT) In-Reply-To: <012fd35d-96fd-4775-835e-2105176c4f97@isocpp.org> X-Original-Sender: vlad.moscow@mail.ru Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:19208 Archived-At: ------=_Part_666_974218136.1437674258041 Content-Type: multipart/alternative; boundary="----=_Part_667_1843617176.1437674258041" ------=_Part_667_1843617176.1437674258041 Content-Type: text/plain; charset=UTF-8 Another example #include #include #include namespace std { template Iterator begin( const std::pair &p ) { return p.first; } template Iterator end( const std::pair &p ) { return p.second; } } int main() { std::vector v = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }; for ( auto x : std::make_pair( v.begin(), v.end() ) ) std::cout << x << ' '; std::cout << std::endl; for ( auto x : std::make_pair( v.rbegin(), v.rend() ) ) std::cout << x << ' '; std::cout << std::endl; } The program output is 0 1 2 3 4 5 6 7 8 9 9 8 7 6 5 4 3 2 1 0 Enjoy!:) On Thursday, July 23, 2015 at 8:36:46 PM UTC+3, Vlad from Moscow wrote: > I'd like to suggest very simple and at the same time very useful > overloaded functions std::begin and std::end for standard class std::pair. > > Here is a demonstrative program of the idea > > #include > #include > > namespace std > { > template > Iterator begin( const std::pair &p ) > { > return p.first; > } > template > Iterator end( const std::pair &p ) > { > return p.second; > } > } > > int main() > { > int a[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }; > > for ( auto x : std::make_pair( a + 3, a + 7 ) ) std::cout << x << ' '; > std::cout << std::endl; > > int b[][3] = { { 1, 2, 3 }, { 4, 5, 6 } }; > > for ( auto x : std::make_pair( b[0] + 1, b[1] + 2 ) ) std::cout << x > << ' '; > std::cout << std::endl; > } > > The program output is > > 3 4 5 6 > 2 3 4 5 > -- --- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an email to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/. ------=_Part_667_1843617176.1437674258041 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Another example

#include <= ;iostream>
#include <utility>
#include <vector>
<= div>
namespace std
{=C2=A0=C2=A0=C2=A0

=
template <class Iterator>
Iterator begin( const std::pa= ir<Iterator, Iterator> &p )
{
=C2=A0=C2=A0=C2=A0 return p.f= irst;
}

template <class Iterator>
Iter= ator end( const std::pair<Iterator, Iterator> &p )
{
=C2=A0= =C2=A0=C2=A0 return p.second;
}

}

int main()
{
=C2=A0=C2=A0=C2=A0 std::vector<int>= ; v =3D { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
=C2=A0=C2=A0=C2=A0
=C2=A0= =C2=A0=C2=A0 for ( auto x : std::make_pair( v.begin(), v.end() ) ) std::cou= t << x << ' ';
=C2=A0=C2=A0=C2=A0 std::cout <<= std::endl;
=C2=A0=C2=A0=C2=A0
=C2=A0=C2=A0=C2=A0 for ( auto x : std= ::make_pair( v.rbegin(), v.rend() ) ) std::cout << x << ' &= #39;;
=C2=A0=C2=A0=C2=A0 std::cout << std::endl;
}=C2=A0= =C2=A0=C2=A0

The program output is
=
0 1 2 3 4 5 6 7 8 9
9 8 7 6 5 4 3 2 1 0

Enjoy!:)

On Thursday, July 23, 2015 at 8:36:46 PM UTC+3, Vl= ad from Moscow wrote:
I'd like to =C2=A0suggest very simple and=C2=A0at the same time very= useful=C2=A0 overloaded functions std::begin and std::end for standard cla= ss std::pair.

Here is a demonstrative program of t= he idea

#include <iostream>
#inclu= de <utility>

namespace std
{=C2=A0=C2=A0= =C2=A0
template <class Iterator>
Iterator begin( const std::pa= ir<Iterator, Iterator> &p )
{
=C2=A0=C2=A0=C2=A0 return p.f= irst;
}
template <class Iterator>
Iterator end( const= std::pair<Iterator, Iterator> &p )
{
=C2=A0=C2=A0=C2=A0 re= turn p.second;
}
}

int main()
{
=C2=A0= =C2=A0=C2=A0 int a[] =3D { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
=C2=A0=C2=A0= =C2=A0
=C2=A0=C2=A0=C2=A0 for ( auto x : std::make_pair( a + 3, a + 7 )= ) std::cout << x << ' ';
=C2=A0=C2=A0=C2=A0 std::co= ut << std::endl;
=C2=A0=C2=A0=C2=A0=C2=A0
=C2=A0=C2=A0= =C2=A0 int b[][3] =3D { { 1, 2, 3 }, { 4, 5, 6 } };
=C2=A0=C2=A0= =C2=A0=C2=A0
=C2=A0=C2=A0=C2=A0 for ( auto x : std::make_pair( b[0] + 1,= b[1] + 2 ) ) std::cout << x << ' ';
=C2=A0=C2=A0=C2= =A0 std::cout << std::endl;
}

The program= output is

3 4 5 6
2 3 4 5=C2=A0=C2=A0=C2=A0 <= br>

--

---
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+unsubscribe@isocpp.org.
To post to this group, send email to std-proposals@isocpp.org.
Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/<= /a>.
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