220 22025 article Path: news.gmane.org!not-for-mail From: Sam Kellett Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: New compound assignment operators.:) Date: Tue, 27 Oct 2015 20:37:41 +0000 Lines: 97 Approved: news@gmane.org Message-ID: References: <6b98496b-ea50-4155-8560-4fd0d445a5c5@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=001a11402550a8b87c05231c0c02 X-Trace: ger.gmane.org 1445978266 8391 80.91.229.3 (27 Oct 2015 20:37:46 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 27 Oct 2015 20:37:46 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDY6DWXBQIPRBFWBX6YQKGQEYIVF5EY@isocpp.org Tue Oct 27 21:37:44 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lf0-f70.google.com ([209.85.215.70]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZrB03-0001RB-Q1 for gclcip-std-proposals@m.gmane.org; Tue, 27 Oct 2015 21:37:43 +0100 Original-Received: by lfu67 with SMTP id 67sf72834815lfu.2 for ; Tue, 27 Oct 2015 13:37:43 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:content-type:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=+XmVESY++1+YacjBYuIG7yG7jcTMKZAmbttf9alOxOI=; b=CWMMYIPKGQ21xdzMIC2iXqZ6oaQf89vBeKOZ+I061NV/XB6ruNpVLTgAdE1NZMuugb cxmCTfSfIVqIvTWuVmKcGssPYdqkDWLnDSvm33kkmYQEprAWY2W4sX8IDPta/x2xud+S Kv7CHKNOIP4AAgbRMKR6NfEjezmnSUWWKwe0QnRgNNbmyuu24CAjaL9tt3GYZW5ePtBB S2vPrvljjWb/69epOOlM+R0Vg966RDptAq7FVEOV+1C0S19D1V6958GiK85UlB1zE18r U/J0vtlhgLAMa+OIxRzFHsG+OqGd8m6cMtlfLievub/iA+NeM8RbphOKsq53zEpLjrW6 ZkXg== X-Gm-Message-State: ALoCoQnpxGkhD6sTLHp0IYd80xFy3wrIPbrXOqBz56rkwy2LfWc0x5G1kYSBCeV8sMmDcj9kHedA X-Received: by 10.180.210.212 with SMTP id mw20mr5953855wic.3.1445978263329; Tue, 27 Oct 2015 13:37:43 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.25.159.2 with SMTP id i2ls283314lfe.56.gmail; Tue, 27 Oct 2015 13:37:42 -0700 (PDT) X-Received: by 10.112.149.5 with SMTP id tw5mr20936505lbb.50.1445978262095; Tue, 27 Oct 2015 13:37:42 -0700 (PDT) Original-Received: from mail-lf0-x233.google.com (mail-lf0-x233.google.com. [2a00:1450:4010:c07::233]) by mx.google.com with ESMTPS id g32si26091045lfi.87.2015.10.27.13.37.42 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 27 Oct 2015 13:37:42 -0700 (PDT) Received-SPF: pass (google.com: domain of samkellett@gmail.com designates 2a00:1450:4010:c07::233 as permitted sender) client-ip=2a00:1450:4010:c07::233; Original-Received: by lffz202 with SMTP id z202so178768217lff.3 for ; Tue, 27 Oct 2015 13:37:42 -0700 (PDT) X-Received: by 10.25.28.131 with SMTP id c125mr11205898lfc.99.1445978261991; Tue, 27 Oct 2015 13:37:41 -0700 (PDT) Original-Received: by 10.114.245.165 with HTTP; Tue, 27 Oct 2015 13:37:41 -0700 (PDT) In-Reply-To: <6b98496b-ea50-4155-8560-4fd0d445a5c5@isocpp.org> X-Original-Sender: samkellett@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of samkellett@gmail.com designates 2a00:1450:4010:c07::233 as permitted sender) smtp.mailfrom=samkellett@gmail.com; dkim=pass header.i=@gmail.com; dmarc=pass (p=NONE dis=NONE) header.from=gmail.com 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:22025 Archived-At: --001a11402550a8b87c05231c0c02 Content-Type: text/plain; charset=UTF-8 On 27 October 2015 at 20:27, Vlad from Moscow wrote: > It is enough often when I am writing a predicate for an algorithm I need > to return the result of a comparison or other logical operator. But before > to return the result I need to do some action with one of arguments or a > captured cariable that takes part in the logical expression. So I have to > introduce a boolean variable that to keep the result then do the action and > only after that return the result. > > The idea came to my head when I was answering the following question at SO > http://stackoverflow.com/questions/33375769/a-zero-indexed-array-given-an-equilibrium-index-of-this-array/33376721#33376721 > > Instead of writing three statements in the if statement > > for ( size_t i = 0; i < sizeof( a ) / sizeof( *a ); i++ ) > { > right_sum -= a[i]; > if ( left_sum == right_sum ) std::cout << i << ' '; > left_sum += a[i]; > } > > I could write only one statement :) > > for ( size_t i = 0; i < sizeof( a ) / sizeof( *a ); i++ ) > { > if ( ( left_sum =+ a[i] ) == ( right_sum -= a[i] ) ) std::cout << > i << ' '; > } > what's wrong with writing three statements? -- --- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. 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On 27 October 2015 at 20:27, Vlad from Moscow <vlad.mos= cow@mail.ru> wrote:
It is enough often=C2=A0=C2=A0when I am writing a predic= ate for an algorithm I need to return the result of a comparison or other l= ogical operator. But before to return the result I need to do some action w= ith one of arguments or a captured cariable that takes part in the logical = expression. So I have to introduce a boolean variable that to keep the resu= lt then do the action and only after that return the result.

=

Instead of writing three statements in the if statement

=C2=A0=C2=A0=C2=A0 for ( size_t i =3D 0; i &l= t; sizeof( a ) / sizeof( *a ); i++ )
=C2=A0=C2=A0=C2=A0 {
=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 right_sum -=3D a[i];
=C2=A0=C2=A0=C2= =A0=C2=A0=C2=A0=C2=A0=C2=A0 if ( left_sum =3D=3D right_sum )=C2=A0std::cout= << i << ' ';
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 left_sum +=3D a[i];
=C2=A0=C2=A0=C2=A0 }
=C2= =A0
I could write only one statement :)

= =C2=A0=C2=A0=C2=A0 for ( size_t i =3D 0; i < sizeof( a ) / sizeof( *a );= i++ )
=C2=A0=C2=A0=C2=A0 {
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0 if ( ( left_sum =3D+ a[i]=C2=A0)=C2=A0=3D=3D ( right_sum -=3D a[i] ) )= =C2=A0std::cout << i << ' ';
=C2=A0=C2=A0=C2=A0 }

what's wrong with writing three statements?
=

--

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