Re: un-catched Exceptions in mixed C/C++ code

From:
Pete Becker <pete@versatilecoding.com>
Newsgroups:
comp.lang.c++
Date:
Tue, 18 Dec 2007 13:54:18 -0500
Message-ID:
<2007121813541875249-pete@versatilecodingcom>
On 2007-12-18 13:22:29 -0500, Kira Yamato <kirakun@earthlink.net> said:

On 2007-12-18 13:10:43 -0500, wrungel <wrungel@web.de> said:

On 18 Dez., 19:05, Kira Yamato <kira...@earthlink.net> wrote:

How did you get the linker to be able to let the C translation unit
(y.c) see the C++ function in the C++ translation unit (z.cc)?

Sorry that I couldn't refer to your source code. My Mac cannot
recognize the gtar format.


Using extern "C" declarations for y_func() and z_func().

I uploaded same code as zip archive:
http://freenet-homepage.de/wrungel/exceptions.zip


I think this is the problem: you've declared z_func() with extern "C".


No, that's got nothing to do with it.

The following test program

#include <iostream>

using namespace std;

extern "C"
{
        void callc()
        {
                throw "oh no!";
        }
};

int main()
{
        callc();
        return 0;
}

causes the runtime error message:

terminate called after throwing an instance of 'char const*'
Abort trap


As it should. There's no catch clause. If you wrap the call to callc()
in a try/catch block, this will work just fine.

So, I suppose declaring a function extern "C" changes the way it uses
the stack; hence giving you problems when that function throws an
exception.


No, extern "C" functions can still throw and catch exceptions if
they're compiled as C++.

It seems that there is no way to throw an exception across a stack
frame involving a genuine C function.


That's a different matter. A C function, compiled with a C compiler,
doesn't know anything about exceptions.

--
  Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)

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