220 19210 article Path: news.gmane.org!not-for-mail From: "T. C." Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Overloading std::begin and std::end for std::pair Date: Thu, 23 Jul 2015 11:52:23 -0700 (PDT) Lines: 247 Approved: news@gmane.org Message-ID: References: <012fd35d-96fd-4775-835e-2105176c4f97@isocpp.org> <70492682-c1ac-4d67-9c00-fe8d841aae63@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_756_1165770198.1437677543648" X-Trace: ger.gmane.org 1437677551 19731 80.91.229.3 (23 Jul 2015 18:52:31 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 23 Jul 2015 18:52:31 +0000 (UTC) Cc: vlad.moscow@mail.ru To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCQ43G7NQIIRB2HPYSWQKGQEKZQCSGA@isocpp.org Thu Jul 23 20:52:28 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-vn0-f69.google.com ([209.85.216.69]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZILbW-00041n-3R for gclcip-std-proposals@m.gmane.org; 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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:19210 Archived-At: ------=_Part_756_1165770198.1437677543648 Content-Type: multipart/alternative; boundary="----=_Part_757_2023590488.1437677543648" ------=_Part_757_2023590488.1437677543648 Content-Type: text/plain; charset=UTF-8 http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#1381 On Thursday, July 23, 2015 at 2:30:02 PM UTC-4, Vlad from Moscow wrote: > > And one more example :) > > #include > #include > #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 = { 3, 4, 0, 5, 1, 6, 9, 7, 8 }; > > for ( auto x : v ) std::cout << x << ' '; > std::cout << std::endl; > auto p = std::minmax_element( v.begin(), v.end() ); > > if ( std::distance( v.begin(), p.second ) < std::distance( v.begin(), > p.first ) ) > { > std::swap( p.first, p.second ); > } > for ( auto x : p ) std::cout << x << ' '; > std::cout << std::endl; > } > > The program output is > > 3 4 0 5 1 6 9 7 8 > 0 5 1 6 > > On Thursday, July 23, 2015 at 8:57:38 PM UTC+3, Vlad from Moscow wrote: > >> 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_757_2023590488.1437677543648 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defec= ts.html#1381


On Thursday, July= 23, 2015 at 2:30:02 PM UTC-4, Vlad from Moscow wrote:
And one more example :)
=

#include <iostream>
#include <utility>#include <vector>
#include <algorithm>
#include <ite= rator>

namespace std
{=C2=A0=C2=A0=C2=A0 template <class Iterator>
Iterator begin( const std::pair<Iter= ator, Iterator> &p )
{
=C2=A0=C2=A0=C2=A0 return p.first;
}=
template <class Iterator>
Iterator end( const std::pair= <Iterator, Iterator> &p )
{
=C2=A0=C2=A0=C2=A0 return p.sec= ond;
}
}
int main()
{
=C2=A0=C2=A0=C2=A0 std::vector&= lt;int> v =3D { 3, 4, 0, 5, 1, 6, 9, 7, 8 };
=C2=A0=C2=A0=C2=A0
= =C2=A0=C2=A0=C2=A0 for ( auto x : v ) std::cout << x << ' &= #39;;
=C2=A0=C2=A0=C2=A0 std::cout << std::endl;
=C2=A0= =C2=A0=C2=A0 auto p =3D std::minmax_element( v.begin(), v.end() );
=C2= =A0=C2=A0=C2=A0
=C2=A0=C2=A0=C2=A0 if ( std::distance( v.begin(), p.sec= ond ) < std::distance( v.begin(), p.first ) )
=C2=A0=C2=A0=C2=A0 {=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 std::swap( p.first, p.second );=
=C2=A0=C2=A0=C2=A0 }=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0
=C2=A0=C2=A0=C2=A0 for ( auto x : p ) std::cout << x << '= ; ';
=C2=A0=C2=A0=C2=A0 std::cout << std::endl;
= }=C2=A0=C2=A0=C2=A0

The program output is

=
3 4 0 5 1 6 9 7 8
0 5 1 6

On Thursday, July 23= , 2015 at 8:57:38 PM UTC+3, Vlad from Moscow wrote:
=
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 l= ike to =C2=A0suggest very simple and=C2=A0at the same time very useful=C2= =A0 overloaded functions std::begin and std::end for standard class std::pa= ir.

Here is a demonstrative program of the idea

#include <iostream>
#include <uti= lity>

namespace std
{=C2=A0=C2=A0=C2=A0
= template <class Iterator>
Iterator begin( const std::pair<Itera= tor, Iterator> &p )
{
=C2=A0=C2=A0=C2=A0 return p.first;
}<= /div>
template <class Iterator>
Iterator end( const std::pair&= lt;Iterator, Iterator> &p )
{
=C2=A0=C2=A0=C2=A0 return p.seco= nd;
}
}

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::co= ut << x << ' ';
=C2=A0=C2=A0=C2=A0 std::cout <<= ; 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<= br>=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

--

---
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To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+unsubscribe@isocpp.org.
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