C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Calling C++ from C          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message Joseph Seigh Guest Posted: Thu Jan 20, 2005 1:01 am    Post subject: Calling C++ from C I'm trying to write some C++ library routines callable by C. The functions are declared extern "C" but I'm getting the loader complaining it can't resolve new() and delete(). Am I just missing a library or is the C++ runtime environment also an issue? Compiling the C program as a C++ program seems to work but I'd rather have the library look like a plain C library. -- Joe Seigh Back to top Victor Bazarov Guest Posted: Thu Jan 20, 2005 1:31 am    Post subject: Re: Calling C++ from C "Joseph Seigh" <jseigh_01 (AT) xemaps (DOT) com> wrote... Quote: I'm trying to write some C++ library routines callable by C. The functions are declared extern "C" but I'm getting the loader complaining it can't resolve new() and delete(). Am I just missing a library or is the C++ runtime environment also an issue? Run-time is probably not an issue, but a C++ library is probably missing. If it's gcc/g++ you're using, try linking using g++. Quote: Compiling the C program as a C++ program seems to work but I'd rather have the library look like a plain C library. Why? Back to top Joseph Seigh Guest Posted: Thu Jan 20, 2005 1:54 am    Post subject: Re: Calling C++ from C On Wed, 19 Jan 2005 20:31:59 -0500, Victor Bazarov <v.Abazarov (AT) comAcast (DOT) net> wrote: Quote: "Joseph Seigh" <jseigh_01 (AT) xemaps (DOT) com> wrote... Compiling the C program as a C++ program seems to work but I'd rather have the library look like a plain C library. Why? So the library can have a C api. It's easier to write it in C++ since I have the C++ classes to do it are already written. I could rewrite the C++ classes in pseudo object oriented C code but that would be pretty tedious considering the C++ classes are smart pointer classes. -- Joe Seigh Back to top Victor Bazarov Guest Posted: Thu Jan 20, 2005 2:17 am    Post subject: Re: Calling C++ from C "Joseph Seigh" <jseigh_01 (AT) xemaps (DOT) com> wrote... Quote: On Wed, 19 Jan 2005 20:31:59 -0500, Victor Bazarov [email]v.Abazarov (AT) comAcast (DOT) net[/email]> wrote: "Joseph Seigh" <jseigh_01 (AT) xemaps (DOT) com> wrote... Compiling the C program as a C++ program seems to work but I'd rather have the library look like a plain C library. Why? So the library can have a C api. It's easier to write it in C++ since I have the C++ classes to do it are already written. I could rewrite the C++ classes in pseudo object oriented C code but that would be pretty tedious considering the C++ classes are smart pointer classes. Let me get this straight. The library has a C interface. But it'll be impossible to use from C due to the same problem you yourself encountered (missing libraries when linking). So, it will only be useful within a C++ project/program. Why not do the users of it a favour and leave it C++? Back to top Joseph Seigh Guest Posted: Thu Jan 20, 2005 3:35 am    Post subject: Re: Calling C++ from C On Wed, 19 Jan 2005 21:17:46 -0500, Victor Bazarov <v.Abazarov (AT) comAcast (DOT) net> wrote: Quote: "Joseph Seigh" <jseigh_01 (AT) xemaps (DOT) com> wrote... On Wed, 19 Jan 2005 20:31:59 -0500, Victor Bazarov [email]v.Abazarov (AT) comAcast (DOT) net[/email]> wrote: Why? So the library can have a C api. It's easier to write it in C++ since I have the C++ classes to do it are already written. I could rewrite the C++ classes in pseudo object oriented C code but that would be pretty tedious considering the C++ classes are smart pointer classes. Let me get this straight. The library has a C interface. But it'll be impossible to use from C due to the same problem you yourself encountered (missing libraries when linking). So, it will only be useful within a C++ project/program. Why not do the users of it a favour and leave it C++? So the library can have wider application. The implication here is I should write libraries in C to begin with since I can use them to write either C or C++ applications or libraries, but the converse is not true. Which is too bad since I tend towards OO in design and would rather not write everything twice, once in C and once in C++. -- Joe Seigh Back to top Victor Bazarov Guest Posted: Thu Jan 20, 2005 3:38 am    Post subject: Re: Calling C++ from C "Joseph Seigh" <jseigh_01 (AT) xemaps (DOT) com> wrote... Quote: [..] The implication here is I should write libraries in C to begin with since I can use them to write either C or C++ applications or libraries, but the converse is not true. Which is too bad since I tend towards OO in design and would rather not write everything twice, once in C and once in C++. I sympathise, believe me. But it seems that even if you "limit" yourself to doing only C++-targeted libraries, you're not going to miss too big a segment of the market. Back to top E. Robert Tisdale Guest Posted: Thu Jan 20, 2005 3:42 am    Post subject: Re: Calling C++ from C Joseph Seigh wrote: Quote: Victor Bazarov wrote: Joseph Seigh wrote: Victor Bazarov wrote: Why? So the library can have a C api. It's easier to write it in C++ since I have the C++ classes to do it are already written. I could rewrite the C++ classes in pseudo object oriented C code but that would be pretty tedious considering the C++ classes are smart pointer classes. Let me get this straight. The library has a C interface. But it'll be impossible to use from C due to the same problem you yourself encountered (missing libraries when linking). So, it will only be useful within a C++ project/program. Why not do the users of it a favour and leave it C++? So the library can have wider application. The implication here is I should write libraries in C to begin with since I can use them to write either C or C++ applications or libraries, but the converse is not true. Which is too bad since I tend towards OO in design and would rather not write everything twice, once in C and once in C++. I think that you may be confused. You can write a C library that you can compile with either a C compiler or a C++ compiler. You could have one object code library archive for C programmers and a different object code library archive for C++ programmers both of which are derived from exactly the same source code repository. Back to top Joseph Seigh Guest Posted: Thu Jan 20, 2005 4:10 am    Post subject: Re: Calling C++ from C On Wed, 19 Jan 2005 22:38:59 -0500, Victor Bazarov <v.Abazarov (AT) comAcast (DOT) net> wrote: Quote: "Joseph Seigh" <jseigh_01 (AT) xemaps (DOT) com> wrote... [..] The implication here is I should write libraries in C to begin with since I can use them to write either C or C++ applications or libraries, but the converse is not true. Which is too bad since I tend towards OO in design and would rather not write everything twice, once in C and once in C++. I sympathise, believe me. But it seems that even if you "limit" yourself to doing only C++-targeted libraries, you're not going to miss too big a segment of the market. It's multithreading stuff which mostly gets done in C at this point. In this case, it's form of proxy GC based on atomic_ptr and I was trying to put the api for it in the same form as the RCU for preemptive user threads api so you could use either without changing code logic. Let's you do things like AB testing. The atomic_ptr stuff runs faster but that's on a uniprocessor. Actually, it's an ABC test, C is using mutexes which is way slower. -- Joe Seigh Back to top Dietmar Kuehl Guest Posted: Thu Jan 20, 2005 7:27 am    Post subject: Re: Calling C++ from C Joseph Seigh wrote: Quote: I'm trying to write some C++ library routines callable by C. The functions are declared extern "C" but I'm getting the loader complaining it can't resolve new() and delete(). Am I just missing a library or is the C++ runtime environment also an issue? You need to perform the link step with a C++ aware tool, typically with the C++ compiler. This has the fact of linking the C++ standard library and possibly other stuff like instantiating necessary templates. -- <mailto:dietmar_kuehl (AT) yahoo (DOT) com> <http://www.dietmar-kuehl.de/> <http://www.contendix.com> - Software Development & Consulting Back to top Karl Heinz Buchegger Guest Posted: Thu Jan 20, 2005 1:28 pm    Post subject: Re: Calling C++ from C Joseph Seigh wrote: Quote: On Wed, 19 Jan 2005 21:17:46 -0500, Victor Bazarov <v.Abazarov (AT) comAcast (DOT) net> wrote: "Joseph Seigh" <jseigh_01 (AT) xemaps (DOT) com> wrote... On Wed, 19 Jan 2005 20:31:59 -0500, Victor Bazarov [email]v.Abazarov (AT) comAcast (DOT) net[/email]> wrote: Why? So the library can have a C api. It's easier to write it in C++ since I have the C++ classes to do it are already written. I could rewrite the C++ classes in pseudo object oriented C code but that would be pretty tedious considering the C++ classes are smart pointer classes. Let me get this straight. The library has a C interface. But it'll be impossible to use from C due to the same problem you yourself encountered (missing libraries when linking). So, it will only be useful within a C++ project/program. Why not do the users of it a favour and leave it C++? So the library can have wider application. But it can't. There is no way around it. If it is implemented in C++, then the user of your library has no other choice then to link the C++ runtime in, even if he is programming in C. Here is the deal: What if I have a C compiler only? Then you sold me a library which is useless for me because I cannot link to it because of the missing C++ runtime library. So it turns out that I need to by the C++ compiler (from the same vendor and hopefully their C library and C++ library are compatible) also, just in order to link to your library. But then: what is hindering me to use the C++ compiler in the first place? But then the next question is: If I am limited to C++ anyway, why did you restrict yourself to a C API only? See. When using C++ as implementation language with a C style interface you have gained nothing et all. I am still forced to use a C++ compiler. -- Karl Heinz Buchegger [email]kbuchegg (AT) gascad (DOT) at[/email] Back to top Joseph Seigh Guest Posted: Thu Jan 20, 2005 3:05 pm    Post subject: Re: Calling C++ from C On Thu, 20 Jan 2005 14:28:42 +0100, Karl Heinz Buchegger <kbuchegg (AT) gascad (DOT) at> wrote: Quote: Joseph Seigh wrote: On Wed, 19 Jan 2005 21:17:46 -0500, Victor Bazarov <v.Abazarov (AT) comAcast (DOT) net> wrote: Let me get this straight. The library has a C interface. But it'll be impossible to use from C due to the same problem you yourself encountered (missing libraries when linking). So, it will only be useful within a C++ project/program. Why not do the users of it a favour and leave it C++? So the library can have wider application. But it can't. There is no way around it. If it is implemented in C++, then the user of your library has no other choice then to link the C++ runtime in, even if he is programming in C. Here is the deal: What if I have a C compiler only? Then you sold me a library which is useless for me because I cannot link to it because of the missing C++ runtime library. So it turns out that I need to by the C++ compiler (from the same vendor and hopefully their C library and C++ library are compatible) also, just in order to link to your library. But then: what is hindering me to use the C++ compiler in the first place? But then the next question is: If I am limited to C++ anyway, why did you restrict yourself to a C API only? See. When using C++ as implementation language with a C style interface you have gained nothing et all. I am still forced to use a C++ compiler. You're missing the point. The bulk of the applications that would use the api are written in C. If I restrict the api to C++, I lose most of those applications since most multi-threading applications are written in C. The stuff I'm planning to do is here http://atomic-ptr-plus.sourceforge.net/ subject to change. I'll have to seriously consider rewriting atomic_ptr in C. It'd be a lot more awkard to use but it might be worth it to avoid C++ controversy. -- Joe Seigh Back to top msalters Guest Posted: Thu Jan 20, 2005 4:13 pm    Post subject: Re: Calling C++ from C Joseph Seigh wrote: Quote: I'm trying to write some C++ library routines callable by C. The functions are declared extern "C" but I'm getting the loader complaining it can't resolve new() and delete(). Am I just missing a library or is the C++ runtime environment also an issue? Compiling the C program as a C++ program seems to work but I'd rather have the library look like a plain C library. If you're compiling C++, you'll have to include the C++ Standard at some point. Now, you're getting close to off-topic because you're building something without a main(), but anyway: when compiling a DLL you end up with two link steps. If you can't include the C++ lib in the second (dynamic) link fase, you must link it in the first (static) link fase. Of course, no guarantees yet, libraries are not yet in ISO C++, and mixed-lang programming is always implementation-defined. Regards, Michiel Salters Back to top Markus Elfring Guest Posted: Fri Feb 11, 2005 9:12 pm    Post subject: Re: Calling C++ from C Quote: I'm trying to write some C++ library routines callable by C. The functions are declared extern "C" but I'm getting the loader complaining it can't resolve new() and delete(). Am I just missing a library or is the C++ runtime environment also an issue? Compiling the C program as a C++ program seems to work but I'd rather have the library look like a plain C library. Would you like to apply the techniques that are described by Matthew Wilson in the sections "7.4 I Can C Clearly Now" and "7.4.4 Getting a Handle on C++ Classes" of the book "Imperfect C++" (ISBN 0-321-22877-4) for your evolving library? http://atomic-ptr-plus.sourceforge.net/ Regards, 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.