C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  name mangling of functions          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Guest Posted: Tue Dec 19, 2006 10:10 am    Post subject: name mangling of functions Hi Everyone, I read somwhere that c++ compiler does name mangling of functions which is why c source code can't invoke functions from object files that were generated using c++ compiler. Can anyone tell in detail as to what name mangling is all about? Back to top Alan Johnson Guest Posted: Tue Dec 19, 2006 10:10 am    Post subject: Re: name mangling of functions sam_cit (AT) yahoo (DOT) co.in wrote: Quote: Hi Everyone, I read somwhere that c++ compiler does name mangling of functions which is why c source code can't invoke functions from object files that were generated using c++ compiler. Can anyone tell in detail as to what name mangling is all about? In C, functions all exist in the global namespace. You can have only one function with a particular name throughout your entire program. In C++, you may have indefinitely many functions with the same name, so long as each is in a different namespace, class, etc, or even in the same namespace if they differ in the number or type of arguments. Clearly, its name alone is no longer sufficient for a linker to uniquely identify a function, so some C++ compilers solve this problem by giving functions that have the same name in the source code some mangled name in the object file. This mangled name might take into account the class, namespace, and number and type of arguments the function has so that each function with the same name will have a different mangled name. Note, however, that how this is done (or whether it is done at all) is an implementation detail. The standard doesn't say anything about name mangling. -- Alan Johnson Back to top Guest Posted: Tue Dec 19, 2006 10:10 am    Post subject: Re: name mangling of functions Quote: In C, functions all exist in the global namespace. You can have only one function with a particular name throughout your entire program. In C++, you may have indefinitely many functions with the same name, so long as each is in a different namespace, class, etc, or even in the same namespace if they differ in the number or type of arguments. Clearly, its name alone is no longer sufficient for a linker to uniquely identify a function, so some C++ compilers solve this problem by giving functions that have the same name in the source code some mangled name in the object file. This mangled name might take into account the class, namespace, and number and type of arguments the function has so that each function with the same name will have a different mangled name. Does it mean name mangling is also done for variables? and if i have only one function definition for a particular function name, will the compiler perform name mangling? Back to top Erik Wikström Guest Posted: Tue Dec 19, 2006 10:10 am    Post subject: Re: name mangling of functions On Dec 19, 9:07 am, sam_...@yahoo.co.in wrote: Quote: In C, functions all exist in the global namespace. You can have only one function with a particular name throughout your entire program. In C++, you may have indefinitely many functions with the same name, so long as each is in a different namespace, class, etc, or even in the same namespace if they differ in the number or type of arguments. Clearly, its name alone is no longer sufficient for a linker to uniquely identify a function, so some C++ compilers solve this problem by giving functions that have the same name in the source code some mangled name in the object file. This mangled name might take into account the class, namespace, and number and type of arguments the function has so that each function with the same name will have a different mangled name. Does it mean name mangling is also done for variables? and if i have only one function definition for a particular function name, will the compiler perform name mangling? Shouldn't be necessary, and I don't thing any compiler does that, but you never know. -- Erik Wikström Back to top Serge Paccalin Guest Posted: Tue Dec 19, 2006 10:10 am    Post subject: Re: name mangling of functions Le 19.12.2006 09:07, : Quote: Clearly, its name alone is no longer sufficient for a linker to uniquely identify a function, so some C++ compilers solve this problem by giving functions that have the same name in the source code some mangled name in the object file. This mangled name might take into account the class, namespace, and number and type of arguments the function has so that each function with the same name will have a different mangled name. Does it mean name mangling is also done for variables? You might have several variables with the same name: - in different namespaces - as data members in different classes so the compiler needs at least put these in the symbol names. Quote: and if i have only one function definition for a particular function name, will the compiler perform name mangling? The compiler cannot know that, since it compiles one module at a time. Only the linker could know a function name is used for one function. -- ___________ _/ _ \_`_`_`_) Serge PACCALIN -- sp ad mailclub.net \ \_L_) Pour bien répondre avec Google, ne pas cliquer -'(__) « Répondre », mais « Afficher les options », _/___(_) puis cliquer « Répondre » (parmi les options). Back to top Markus Moll Guest Posted: Tue Dec 19, 2006 10:10 am    Post subject: Re: name mangling of functions Hi Erik Wikström wrote: Quote: On Dec 19, 9:07 am, sam_...@yahoo.co.in wrote: Does it mean name mangling is also done for variables? and if i have only one function definition for a particular function name, will the compiler perform name mangling? Shouldn't be necessary, and I don't thing any compiler does that, but you never know. Uhm... $ cat t.cc int func(double x) { return 42; } $ g++ -o t.o -c t.cc $ nm t.o U __gxx_personality_v0 00000000 T _Z4funcd "_Z4funcd" looks mangled to me... A compiler can't know if lateron you will link with some other file where something with the same name is defined again. And at least GCC also does not care, even if it knows (int main() { return func(0.0); } added to the program): $ g++ -fwhole-program -o t.o -c t.cc $ nm t.o U __gxx_personality_v0 0000001a T main 00000000 t _Z4funcd Markus 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.