C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Defect: std::endl in (a) 22.2.8/5, (b) 22.2.8/11, (c) 22.2.8          C++Talk.NET Forum Index -> C++ language, library and standards View previous topic :: View next topic   Author Message Alf P. Steinbach Guest Posted: Sun Jan 16, 2005 1:18 am    Post subject: Defect: std::endl in (a) 22.2.8/5, (b) 22.2.8/11, (c) 22.2.8 std::endl is declared by <ostream>, which is not necessarily included by <iostream>. The cited paragraps, (a) 22.2.8/5, (b) 22.2.8/11, (c) 22.2.8/13 and (d) 27.6.1.3/22, contain program examples that use std::endl without including <ostream>, just <iostream>, and even though the unofficial revision list for C++2003 contains a fix for e.g. 22.2.8/11 this issue has not been fixed there (I don't have the C++2003 standard). My suggested resolution is to keep the examples as-is but ensure that the declaration of std::endl is available via <iostream>, since this is commonly assumed, both in textbooks and actual code. Is there any problem in stating that <ostream> is included by <iostream>? Otherwise one can simply state that std::endl is available via <iostream>. -- A: Because it messes up the order in which people normally read text. Q: Why is it such a bad thing? A: Top-posting. Q: What is the most annoying thing on usenet and in e-mail? --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top Alberto Barbati Guest Posted: Sun Jan 16, 2005 5:24 pm    Post subject: Re: Defect: std::endl in (a) 22.2.8/5, (b) 22.2.8/11, (c) 22 Alf P. Steinbach wrote: Quote: std::endl is declared by <ostream>, which is not necessarily included by <iostream>. The cited paragraps, (a) 22.2.8/5, (b) 22.2.8/11, (c) 22.2.8/13 and (d) 27.6.1.3/22, contain program examples that use std::endl without including <ostream>, just <iostream>, and even though the unofficial revision list for C++2003 contains a fix for e.g. 22.2.8/11 this issue has not been fixed there (I don't have the C++2003 standard). Well, if you want to be fussy, it's not a problem of std::endl only. If <iostream> did not eventually include <ostream> then *any* meaningful use of std::cout, including std::cout << "hello, worldn", would be ill-formed, because all the necessary overloads of operator<< are defined in Quote: My suggested resolution is to keep the examples as-is but ensure that the declaration of std::endl is available via <iostream>, since this is commonly assumed, both in textbooks and actual code. Is there any problem in stating that <ostream> is included by <iostream>? Otherwise one can simply state that std::endl is available via <iostream>. Maybe it would simpler to add in the <iostream> synopsis in 27.3 the two lines: #include <istream> #include <ostream> just like the <ios> synopsis in 27.4 explicitly provides #include <iosfwd>. Alberto --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top dietmar_kuehl@yahoo.com Guest Posted: Mon Jan 17, 2005 5:52 pm    Post subject: Re: Defect: std::endl in (a) 22.2.8/5, (b) 22.2.8/11, (c) 22 Alf P. Steinbach wrote: Quote: std::endl is declared by <ostream>, which is not necessarily included by <iostream>. Actually, this is an old problem: I first reported it in 1998 (see: <http://groups-beta.google.com/group/comp.std.c++/msg/6f6abf4bc98c3d20?output=gplain>) but it was always considered to not really be a problem: essentially it was agreed that all implementation are better off doing the right thing. Despite Nathan Myers' claim that there certainly will be a defect report on this issue, I don't think there was ever a defect reported. I never bothered to write a defect, partially because I don't think it is one: I would like to *NOT* include <istream> and/or <ostream> in my implementation when including <iostream>. Essentially, <iostream> is the wrong header in many situations where it currently seems to do the right thing. Unless you need to use one of the eight standard stream objects, you should not include it because a popular initialization technique for these objects takes up some time during start-up and finalization for each translation unit including <iostream>. -- <mailto:dietmar_kuehl (AT) yahoo (DOT) com> <http://www.dietmar-kuehl.de/> <http://www.contendix.com> - Software Development & Consulting --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top dietmar_kuehl@yahoo.com Guest Posted: Mon Jan 17, 2005 5:52 pm    Post subject: Re: Defect: std::endl in (a) 22.2.8/5, (b) 22.2.8/11, (c) 22 Alf P. Steinbach wrote: Quote: The cited paragraps, (a) 22.2.8/5, (b) 22.2.8/11, (c) 22.2.8/13 and (d) 27.6.1.3/22, contain program examples that use std::endl without including <ostream>, just <iostream>, and even though the unofficial revision list for C++2003 contains a fix for e.g. 22.2.8/11 this issue has not been fixed there (I don't have the C++2003 standard). Just another note (I didn't realize that you are actually talking about Chapter 22): all uses of 'std::endl' in the quoted clauses are ill-advised anyway! Especially bad is the first one: 'std::cout' is 'tie()'ed to 'std::cin' and is thus flushed prior to a read attempt on 'std::cin' anyway. Excessive use of 'std::endl' can cause unnecessary performance problems! The only legitimate reason to use 'std::endl' is in my opinion for log files and even for these you are probably better off setting 'std::ios_base::unitbuf' anyway... -- <mailto:dietmar_kuehl (AT) yahoo (DOT) com> <http://www.dietmar-kuehl.de/> <http://www.contendix.com> - Software Development & Consulting --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top Thomas Mang Guest Posted: Mon Jan 17, 2005 10:21 pm    Post subject: Re: Defect: std::endl in (a) 22.2.8/5, (b) 22.2.8/11, (c) 22 <dietmar_kuehl (AT) yahoo (DOT) com> schrieb im Newsbeitrag news:1105974195.033782.304280 (AT) f14g2000cwb (DOT) googlegroups.com... Quote: Alf P. Steinbach wrote: std::endl is declared by <ostream>, which is not necessarily included by <iostream>. Actually, this is an old problem: I first reported it in 1998 (see: http://groups-beta.google.com/group/comp.std.c++/msg/6f6abf4bc98c3d20?outpu t=gplain>) Quote: but it was always considered to not really be a problem: essentially it was agreed that all implementation are better off doing the right thing. Despite Nathan Myers' claim that there certainly will be a defect report on this issue, I don't think there was ever a defect reported. I never bothered to write a defect, partially because I don't think it is one: I would like to *NOT* include <istream> and/or ostream> in my implementation when including <iostream>. Essentially, iostream> is the wrong header in many situations where it currently seems to do the right thing. Unless you need to use one of the eight standard stream objects, you should not include it because a popular initialization technique for these objects takes up some time during start-up and finalization for each translation unit including iostream>. I don't have an opinion if <iostream> should include <ostream> and <istream> [even if I had, it wouldn't matter at all]. Doing it not seems to match with the "Don't pay for something you don't need" rule; and just because many books or references get it wrong, that doesn't mean it's the Standard faults. However, search for examples in the 2003-version of the Standard. I haven't counted, but I think all the first 5 or so I found were wrong, because they included only <iostream>. Now I know examples are non-normative, but frankly, what style does the Standard propagate if it doesn't get it's own code snippets right? I am convinced at least the Standard has to be fixed - whatever the solution might be. Current situation cannot be accepted IMHO. I was also surprised that, although the issue is known for many years now, nobody corrected it in the 2003 review. Thomas --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. 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