C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  multiply defined operator          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Brett Irving Guest Posted: Sun Jun 29, 2003 6:43 am    Post subject: multiply defined operator Hi I keep having problems with trying to overload the << operator, the compiler will not let me define it. the code looks like #ifndef __MYARRAY_H__ #define __MYARRAY_H__ #include .. .. .. .. }; ostream & operator<<(ostream &o, MyArray& m) { return m(o); } #endif It wont work if I put it inside or out of the #endif The error that the compiler keeps giving me is this. ld: fatal: symbol `operator<<(std::basic_ostream std::char_traits&, MyArray&)' is multiply defined: (file MyArrayMain.o and file MyArray.o); ld: fatal: File processing errors. No output written to myarray collect2: ld returned 1 exit status Please help. thanks a lot Back to top John Harrison Guest Posted: Sun Jun 29, 2003 6:58 am    Post subject: Re: multiply defined operator "Brett Irving" <balgorg (AT) hotmail (DOT) com> wrote Quote: Hi I keep having problems with trying to overload the << operator, the compiler will not let me define it. the code looks like #ifndef __MYARRAY_H__ #define __MYARRAY_H__ #include . . . . }; ostream & operator<<(ostream &o, MyArray& m) Should be inline ostream & operator<<(ostream &o, MyArray& m) Also you are ignoring the issue of const, you should write inline ostream & operator<<(ostream &o, const MyArray& m) because you don't change a MyArray when you output it. Although making this change will probably mean that you have to stop ignoring the issue of const in the declaration of MyArray as well. Look on it as a good oppurtunity to learn about const. john Back to top Aggro Guest Posted: Sun Jun 29, 2003 7:07 am    Post subject: Re: multiply defined operator Brett Irving wrote: Quote: #ifndef __MYARRAY_H__ #define __MYARRAY_H__ C++ standard specifically reserves macros with two sequential underscores for use by the implementation. In most cases, there is no problem, but if you want your code to be portable... You will propably do just fine if you write only: #ifndef MYARRAY_H #define MYARRAY_H Back to top Brett Irving Guest Posted: Sun Jun 29, 2003 9:05 am    Post subject: Re: multiply defined operator Thanks Heaps "John Harrison" <john_andronicus (AT) hotmail (DOT) com> wrote Quote: "Brett Irving" <balgorg (AT) hotmail (DOT) com> wrote in message news:4f68b81.0306282243.2133fa8e (AT) posting (DOT) google.com... Hi I keep having problems with trying to overload the << operator, the compiler will not let me define it. the code looks like #ifndef __MYARRAY_H__ #define __MYARRAY_H__ #include . . . . }; ostream & operator<<(ostream &o, MyArray& m) Should be inline ostream & operator<<(ostream &o, MyArray& m) Also you are ignoring the issue of const, you should write inline ostream & operator<<(ostream &o, const MyArray& m) because you don't change a MyArray when you output it. Although making this change will probably mean that you have to stop ignoring the issue of const in the declaration of MyArray as well. Look on it as a good oppurtunity to learn about const. john 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.