C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  static data member lost?          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message JustSomeGuy Guest Posted: Thu Oct 28, 2004 7:48 pm    Post subject: static data member lost? I have a class that has a public data member. If however I declare that data member as being static, then the linker fails and says the symbol is undefined. Must static data members be private? Back to top Victor Bazarov Guest Posted: Thu Oct 28, 2004 7:53 pm    Post subject: Re: static data member lost? JustSomeGuy wrote: Quote: I have a class that has a public data member. If however I declare that data member as being static, then the linker fails and says the symbol is undefined. Must static data members be private? No. But static data members have to be _defined_ at the namespace level. V Back to top JustSomeGuy Guest Posted: Thu Oct 28, 2004 8:17 pm    Post subject: Re: static data member lost? Victor Bazarov wrote: Quote: JustSomeGuy wrote: I have a class that has a public data member. If however I declare that data member as being static, then the linker fails and says the symbol is undefined. Must static data members be private? No. But static data members have to be _defined_ at the namespace level. V Ok I think I see... so if I have a class class myclass { public: static int x; }; main() { myclass c; cout << std::c.x; } Is that correct? Back to top Victor Bazarov Guest Posted: Thu Oct 28, 2004 8:42 pm    Post subject: Re: static data member lost? JustSomeGuy wrote: Quote: Victor Bazarov wrote: JustSomeGuy wrote: I have a class that has a public data member. If however I declare that data member as being static, then the linker fails and says the symbol is undefined. Must static data members be private? No. But static data members have to be _defined_ at the namespace level. V Ok I think I see... so if I have a class class myclass { public: static int x; }; main() { myclass c; cout << std::c.x; } Is that correct? No. First of all, myclass: is still not defined anywhere. Second, what's "std::c.x"? Why is 'c' prefixed with 'std::'? Your object is not in the 'std' namespace, is it? Third, 'cout' is undefined. Did you forget to include every function needs a return value type: "int main()". To define myclass: you need to add this line: int myclass:; somewhere in the same namespace where 'myclass' is defined. V Back to top Mike Wahler Guest Posted: Fri Oct 29, 2004 1:30 am    Post subject: Re: static data member lost? "JustSomeGuy" <NoOne (AT) ucalgary (DOT) ca> wrote Quote: Victor Bazarov wrote: JustSomeGuy wrote: I have a class that has a public data member. If however I declare that data member as being static, then the linker fails and says the symbol is undefined. Must static data members be private? No. But static data members have to be _defined_ at the namespace level. V Ok I think I see... No, I don't think you do. See below. Quote: so if I have a class class myclass { public: static int x; }; main() { myclass c; cout << std::c.x; } Is that correct? No. Did you even try to compile that? It contains several errors. #include class myclass { public: static int x; }; int myclass:; int main() { std::cout << myclass: << 'n'; /* prints 0 */ return 0; } -Mike Quote: Back to top Kante Mamadou Moustapha Guest Posted: Fri Oct 29, 2004 6:20 am    Post subject: Re: static data member lost? Mike Wahler a écrit : Quote: "JustSomeGuy" <NoOne (AT) ucalgary (DOT) ca> wrote in message news:418153E3.C8B51043 (AT) ucalgary (DOT) ca... Victor Bazarov wrote: JustSomeGuy wrote: I have a class that has a public data member. If however I declare that data member as being static, then the linker fails and says the symbol is undefined. Must static data members be private? No. But static data members have to be _defined_ at the namespace level. V Ok I think I see... No, I don't think you do. See below. so if I have a class class myclass { public: static int x; }; main() { myclass c; cout << std::c.x; } Is that correct? No. Did you even try to compile that? It contains several errors. #include class myclass { public: static int x; }; int myclass:; int main() { std::cout << myclass: << 'n'; /* prints 0 */ return 0; } -Mike and he should initialize it before using, yes you can say compiler do it, but not sure, normalization say nothing about that, it depends on the compiler. Back to top Richard Herring Guest Posted: Fri Oct 29, 2004 9:35 am    Post subject: Re: static data member lost? In message <clsqk9$3ne$2 (AT) news (DOT) u-bordeaux.fr>, Kante Mamadou Moustapha <mkante (AT) emi (DOT) u-bordeaux.fr> writes Quote: Mike Wahler a écrit : "JustSomeGuy" <NoOne (AT) ucalgary (DOT) ca> wrote in message news:418153E3.C8B51043 (AT) ucalgary (DOT) ca... Victor Bazarov wrote: JustSomeGuy wrote: I have a class that has a public data member. If however I declare that data member as being static, then the linker fails and says the symbol is undefined. Must static data members be private? No. But static data members have to be _defined_ at the namespace level. V Ok I think I see... No, I don't think you do. See below. so if I have a class class myclass { public: static int x; }; main() { myclass c; cout << std::c.x; } Is that correct? No. Did you even try to compile that? It contains several errors. #include class myclass { public: static int x; }; int myclass:; int main() { std::cout << myclass: << 'n'; /* prints 0 */ return 0; } -Mike and he should initialize it before using, No need. Since it's static, it gets initialised. Quote: yes you can say compiler do it, but not sure, You may not be sure, but the standard is: "The storage for objects with static storage duration (3.7.1) shall be zero-initialized (8.5) before any other initialization takes place." (3.6.2/1) Quote: normalization say nothing about that, it depends on the compiler. ??? -- Richard Herring Back to top Mike Wahler Guest Posted: Fri Oct 29, 2004 4:38 pm    Post subject: Re: static data member lost? "Kante Mamadou Moustapha" <mkante (AT) emi (DOT) u-bordeaux.fr> wrote Quote: Mike Wahler a écrit : "JustSomeGuy" <NoOne (AT) ucalgary (DOT) ca> wrote in message news:418153E3.C8B51043 (AT) ucalgary (DOT) ca... Victor Bazarov wrote: JustSomeGuy wrote: I have a class that has a public data member. If however I declare that data member as being static, then the linker fails and says the symbol is undefined. Must static data members be private? No. But static data members have to be _defined_ at the namespace level. V Ok I think I see... No, I don't think you do. See below. so if I have a class class myclass { public: static int x; }; main() { myclass c; cout << std::c.x; } Is that correct? No. Did you even try to compile that? It contains several errors. #include class myclass { public: static int x; }; int myclass:; int main() { std::cout << myclass: << 'n'; /* prints 0 */ return 0; } -Mike and he should initialize it before using, Only if an initial value of zero is not acceptable. Quote: yes you can say compiler do it, Yes, the language standard requires that it be initialized to zero. Quote: but not sure, normalization say nothing about that, The ISO standard does, in no uncertain terms. Quote: it depends on the compiler. Yes, it depends upon whether the compiler's behavior conforms to the standard. If it does, the object will be zero-initialized. Always. -Mike 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 (comp.lang.c++) 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.