C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  wrong or superfluous semicolon?          C++Talk.NET Forum Index -> C++ Language (Moderated) View previous topic :: View next topic   Author Message Ulrich Eckhardt Guest Posted: Wed Dec 08, 2004 10:56 pm    Post subject: wrong or superfluous semicolon? // Typical example: struct foo { foo(){}; }; Question is, whether the semicolon after the definition of foo's ctor is only unnecessary or plain wrong? thanks Uli -- FAQ: http://parashift.com/c++-faq-lite/ /* bittersweet C++ */ default: break; [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Woodstok Guest Posted: Thu Dec 09, 2004 9:19 am    Post subject: Re: wrong or superfluous semicolon? In other news: Ulrich Eckhardt typed: Quote: // Typical example: struct foo { foo(){}; }; Question is, whether the semicolon after the definition of foo's ctor is only unnecessary or plain wrong? Unnecessary but it won't cause any errors Woodstok [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top loritsch@gmail.com Guest Posted: Thu Dec 09, 2004 9:21 am    Post subject: Re: wrong or superfluous semicolon? Ulrich Eckhardt wrote: Quote: foo(){}; It really depends on what you are trying to do... While it is valid C++, the semicolon after foo(){} merely produces an empty C++ statement after the function definition. Since empty statements are allowed, there is nothing wrong with it. Instead it is merely superfluous. Regards, Michael Loritsch [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top L.Suresh Guest Posted: Thu Dec 09, 2004 9:23 am    Post subject: Re: wrong or superfluous semicolon? The semicolon is unnecessary after the foo constructor. But from compilers viewpoint, the definition of foo is complete after the right brace. Immediately after that it encounters another demarcator ";", but without any intermediate tokens. So the compiler proceeds after the semi colon. IMHO, i think that its ony unnecessary, not wrong. scattering unnecessary ";" may cause some surprise as in : for (;; { } --lsu [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Sharad Kala Guest Posted: Thu Dec 09, 2004 9:23 am    Post subject: Re: wrong or superfluous semicolon? "Ulrich Eckhardt" <doomster (AT) knuut (DOT) de> wrote in message Quote: // Typical example: struct foo { foo(){}; }; Question is, whether the semicolon after the definition of foo's ctor is only unnecessary or plain wrong? Unnecessary. Check the grammar in Annex A of the Standard. Sharad [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top kanze@gabi-soft.fr Guest Posted: Fri Dec 10, 2004 1:47 am    Post subject: Re: wrong or superfluous semicolon? [email]loritsch (AT) gmail (DOT) com[/email] wrote: Quote: Ulrich Eckhardt wrote: foo(){}; It really depends on what you are trying to do... While it is valid C++, the semicolon after foo(){} merely produces an empty C++ statement after the function definition. Since empty statements are allowed, there is nothing wrong with it. Instead it is merely superfluous. This is wrong on two counts. First, the extra semicolon does not create an empty statement. The grammar specifically includes an optional semicolon after an in class member function definition. Secondly, empty statments aren't allowed except in a function definition. A second semicolon would create an empty statement, which is illegal in this context. (I think that some compilers allow empty statements anywhere, however, as an extension.) -- James Kanze GABI Software http://www.gabi-soft.fr Conseils en informatique orientée objet/ Beratung in objektorientierter Datenverarbeitung 9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34 [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Seungbeom Kim Guest Posted: Fri Dec 10, 2004 1:48 am    Post subject: Re: wrong or superfluous semicolon? [email]loritsch (AT) gmail (DOT) com[/email] wrote: Quote: Ulrich Eckhardt wrote: foo(){}; It really depends on what you are trying to do... While it is valid C++, the semicolon after foo(){} merely produces an empty C++ statement after the function definition. Since empty statements are allowed, there is nothing wrong with it. Instead it is merely superfluous. It's not about empty statements here; the location of the semicolon is outside a function body, where statements are not allowed. But it should be about empty member declarations inside a class definition. Just looking at the Annex A of the C++98 standard, an empty member declaration seems possible because of the production member-declaration: decl-specifier-seq(opt) member-declarator-list(opt) ; but Comeau C++ Online doesn't accept the following code: struct foo { foo() { } ; // okay ; // error ; // error }; where the first semicolon is okay but the rest are not. I don't know what's happening here. P.S. Does anyone know why all the hyphens are lost if I copy and paste from the C++98 standard PDF file? If the error is in the file itself, has it been corrected in the 2003 revision? -- Seungbeom Kim [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Francis Glassborow Guest Posted: Fri Dec 10, 2004 1:55 am    Post subject: Re: wrong or superfluous semicolon? In article <31ogb6F3fa8cuU1 (AT) individual (DOT) net>, Ulrich Eckhardt <doomster (AT) knuut (DOT) de> writes Quote: // Typical example: struct foo { foo(){}; }; Question is, whether the semicolon after the definition of foo's ctor is only unnecessary or plain wrong? Read the grammar and you will find that a semicolon in that position is optional (i.e. it isn't plain wrong, just superfluous) -- Francis Glassborow ACCU Author of 'You Can Do It!' see http://www.spellen.org/youcandoit For project ideas and contributions: http://www.spellen.org/youcandoit/projects [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top spuds Guest Posted: Fri Dec 10, 2004 2:06 am    Post subject: Re: wrong or superfluous semicolon? The semicolon is only required after the declaration In your example you are making a definition. Actually it is a combined declaration definition but the compiler views it as a definition. Definitions of functions never require semicolons. If you think about it, whenever you define the function out of line there is never a requirement for a semi colon like this struct foo { foo(); // a declaration }; foo::foo() { // do something here to initialize foo } /* end of definition of out of line function - no semicolon required here because it is defined */ [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Andrey Tarasevich Guest Posted: Fri Dec 10, 2004 2:44 am    Post subject: Re: wrong or superfluous semicolon? Ulrich Eckhardt wrote: Quote: // Typical example: struct foo { foo(){}; }; Question is, whether the semicolon after the definition of foo's ctor is only unnecessary or plain wrong? ... It is unnecessary, but not wrong, as long as the function definition resides inside the class definition. In the namespace scope a similar semicolon (after function definition) would be an error. -- Best regards, Andrey Tarasevich [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Francis Glassborow Guest Posted: Fri Dec 10, 2004 12:30 pm    Post subject: Re: wrong or superfluous semicolon? In article <ac3724db53520b1a24492e787d8cf790 (AT) localhost (DOT) talkaboutprogramming.com>, spuds <stevenhr (AT) kgh (DOT) kari.net> writes Quote: foo::foo() { // do something here to initialize foo /* end of definition of out of line function - no semicolon required here because it is defined */ Actually, it isn't just 'not required' but prohibited. The optional semicolon for a member function definition is just for in-class definitions. Quote: -- Francis Glassborow ACCU Author of 'You Can Do It!' see http://www.spellen.org/youcandoit For project ideas and contributions: http://www.spellen.org/youcandoit/projects [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Ben Hutchings Guest Posted: Thu Dec 16, 2004 6:20 pm    Post subject: Re: wrong or superfluous semicolon? Seungbeom Kim wrote: <snip> Quote: P.S. Does anyone know why all the hyphens are lost if I copy and paste from the C++98 standard PDF file? It is possible that the hyphens are wrongly being treated as "soft hyphens", which mark potential line break points and should appear as hyphens only if they are used as such. Quote: If the error is in the file itself, has it been corrected in the 2003 revision? There is no such error in the 2003 changes prepared by Andrew Koenig, and since the standard itself was prepared by a similar process, I would guess it has been corrected. -- Ben Hutchings This sentence contradicts itself - no actually it doesn't. [ See http://www.gotw.ca/resources/clcm.htm for info about ] [ comp.lang.c++.moderated. First time posters: Do this! ] Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         C++Talk.NET Forum Index -> C++ Language (Moderated) All times are GMT Page 1 of 1   Jump to: Select a forum C/C++----------------C LanguageC Language (Moderated)C++ Language (Moderated)C++ language (comp.lang.c++)C++ language, library and standards Non-English C/C++ Newsgroups----------------C++ (German)C++ (French)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.