Import C++ DLL

[CrowBar]

Thanks, My Prog worked by linking it statically. (Are there any
benefits/drawbacks by using the static/dynamic linking method?)

I changed some settings in VC++ to compile as C.
I then used the 'coffimplib' utility to convert the VC produced 'MyDLL.lib'
to 'MyDLLcoff.lib'.

Below is my revised code;

module ModMyDLL;
import std.c.stdio;
import std.c.windows.windows;
import std.stdio;
import std.gc;

pragma (lib,"MyDLLcoff.lib");
extern(C)
{
 int fnMyDLL();
}

int main(char[][] args)
{
     printf("value=%i\n", fnMyDLL());

     return 0;
}

"Don Clugston" <dac at nospam.com.au> wrote in message
news:f2nh7d$18q2$1 at digitalmars.com...
> Frits van Bommel wrote:
> > CrowBar wrote:
> >> Please bear with me, I'm very new to C/C++ & D.
> >>
> >> I want to Import a function from a DLL made with VC++ express edition
> >> into
> >> D.
> >>
> > [snip]
> >>
> >> The program compiles but does not execute, it returns "Error Access
> >> Violation", (it should display the number 42).
> >>
> >>
> > [snip]
> >>     fnMyDLL = cast(fnMyDLL_fp) GetProcAddress(h, "fnMyDLL");
> >>
> >>     printf("value=%i\n", fnMyDLL());
> > [snip]
> >
> > GetProcAddress is probably returning null, you forgot to check for that.
> > It seems to think the function doesn't exist. The most likely cause is
> > name mangling.
> >
> > Try adding an underscore before the first character in the function
> > name. (IIRC that's the mangling for C functions on Windows)
> >
> > If that didn't work, make sure the function is either compiled as C code
> > or marked 'extern "C"' (directly or in an 'extern "C" {}' block) if it's
> > compiled as C++ code.
>
> It's incredibly painful to get VC++ to produce extern(C) DLLs. It
> insists on doing something like:
> _fnMyDLL at 0
> essentially ignoring the "extern(C)" declaration. All the __declspec
> garbage doesn't do much, either. I keep reverting to .DEF files.
>
> However, it should be quite simple to make a Microsoft name mangler as
> as a compile-time function. Hmmm... would make a nice little project.
> --
> You can also use the coffimplib tool (from the DM ftp site) to convert
> the MS lib to DMD format, and link it statically. Probably easier.