From 4538808028686465174 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,bb04047befc790b4 X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 2001-02-23 11:56:04 PST Return-Path: X-Authentication-Warning: mulga.cs.mu.OZ.AU: fjh set sender to devnull@stump.algebra.com using -f Path: supernews.google.com!sn-xit-03!supernews.com!logbridge.uoregon.edu!newsfeed.stanford.edu!comp-std-cpp-robomod!not-for-mail X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) From: MikeAlpha@NoSpam_csi.com (Martin Aupperle) Newsgroups: comp.std.c++ Subject: Re: empty parameter list and extern "C" Organization: Nikoma Mediaworks GmbH Message-ID: <3a968230.533654664@news.nikoma.de> References: <3a91a017.213629713@news.nikoma.de> X-Trace: news.nikoma.de 982944528 59884 213.54.113.252 (23 Feb 2001 16:08:48 GMT) X-Complaints-To: abuse@nikoma.de NNTP-Posting-Date: Fri, 23 Feb 2001 16:08:48 +0000 (UTC) X-Newsreader: Forte Free Agent 1.21/32.243 Approved: Fergus Henderson , moderator of comp.std.c++ Date: Fri, 23 Feb 2001 13:52:36 CST Lines: 66 Xref: supernews.google.com comp.std.c++:3766 On Thu, 22 Feb 2001 19:32:10 GMT, Jack Klein wrote: > >Understand that C++ does not guarantee interoperability with code >compiled by a C compiler, or even by the same compiler in its C mode, >if it has one. The intent is to provide this capability if possible, >but all that extern "C" is guaranteed to do is provide C linkage. > I understand. So, please look at the following scenario: 1.) I have a very old and mean C-Library (i.e. one that is compiled with a C-compiler). It exposes a header file foo.h that declares a function f like this: void f(); 2.) Since it is a C-Library, I conclude that f can (syntactically) be called with arbitrary arguments. Any C-Program that includes foo.h should be able to do so. 3.) But I have a C++ program and want to use the library. Therefore I say extern "C" { #include "foo.h" } Now I have a function f declared and can use it. BUT NOT with arbitrary parameters! 4.) It is also not possible to declare f myself, as for example like this extern "C" void f(...); because then I cannot include foo.h with all the rest of the functions any more. (Overloading is not possible with extern "C" - that's understandable).. So - what is the solution? I probably can introduce a cpp-file that does nothing but declare f like in 4.), define another function f2 like void f2(...); that does nothing except calling f. But will the parameters be correctly passed? I think not necessarily, because f2 has c++ linkage and f has c linkage. ------------------------------------------------ Martin Aupperle MikeAlpha@NoSpam_csi.com (remove NoSpam_) ------------------------------------------------ --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.research.att.com/~austern/csc/faq.html ] [ Note that the FAQ URL has changed! Please update your bookmarks. ]