I have a dll that consists of unmanaged C++ routines. I can call a function
in the dll from a C++ executable, but not from a C# executable. I am calling
an independent function, not a class. C# gives me a runtime exception saying
the entry point to the dll cannot be found.

I declare the function in C# with the following lines:
[DllImport("simpleDLL.dll", CallingConvention=CallingConvention.Cdecl)]
public static extern int fnsimpleDLL(int i);

I then call the function with the line:
fnsimpleDLL(1);

Any ideas?

Make sure the exported C function is not mangled (has C linkage), make also
sure the calling convention is cdecl (CallingConvention.Cdecl)]).

Willy.

"Al the programmer" <(E-Mail Removed)> wrote in
message news:1466DA50-01F4-4B7A-9324-(E-Mail Removed)...
>I have a dll that consists of unmanaged C++ routines. I can call a
>function
> in the dll from a C++ executable, but not from a C# executable. I am
> calling
> an independent function, not a class. C# gives me a runtime exception
> saying
> the entry point to the dll cannot be found.
>
> I declare the function in C# with the following lines:
> [DllImport("simpleDLL.dll", CallingConvention=CallingConvention.Cdecl)]
> public static extern int fnsimpleDLL(int i);
>
> I then call the function with the line:
> fnsimpleDLL(1);
>
> Any ideas?

Thanks for the info. I remember the mangling issue from when I had to call C
code from C++, but the C# docs are silent on the issue.

What do I do when I want to export a C++ class in a dll to a C# program?

Al


"Willy Denoyette [MVP]" wrote:

> Make sure the exported C function is not mangled (has C linkage), make also
> sure the calling convention is cdecl (CallingConvention.Cdecl)]).
>
> Willy.
>
> "Al the programmer" <(E-Mail Removed)> wrote in
> message news:1466DA50-01F4-4B7A-9324-(E-Mail Removed)...
> >I have a dll that consists of unmanaged C++ routines. I can call a
> >function
> > in the dll from a C++ executable, but not from a C# executable. I am
> > calling
> > an independent function, not a class. C# gives me a runtime exception
> > saying
> > the entry point to the dll cannot be found.
> >
> > I declare the function in C# with the following lines:
> > [DllImport("simpleDLL.dll", CallingConvention=CallingConvention.Cdecl)]
> > public static extern int fnsimpleDLL(int i);
> >
> > I then call the function with the line:
> > fnsimpleDLL(1);
> >
> > Any ideas?
>
>
>

"Al the programmer" <(E-Mail Removed)> wrote in
message news:017E109C-8812-44AB-B950-(E-Mail Removed)...
> Thanks for the info. I remember the mangling issue from when I had to
> call C
> code from C++, but the C# docs are silent on the issue.
>
> What do I do when I want to export a C++ class in a dll to a C# program?
>
> Al
>
>

Check this....
http://msdn2.microsoft.com/library/e59b22c5.aspx

Willy.

Thanks for the info. The docs don't talk about importing a class, only
functions, but I know where to start looking in the future. For my current
project I need to access C functions, which I can do.

Al

"Willy Denoyette [MVP]" wrote:

>
> "Al the programmer" <(E-Mail Removed)> wrote in
> message news:017E109C-8812-44AB-B950-(E-Mail Removed)...
> > Thanks for the info. I remember the mangling issue from when I had to
> > call C
> > code from C++, but the C# docs are silent on the issue.
> >
> > What do I do when I want to export a C++ class in a dll to a C# program?
> >
> > Al
> >
> >
>
> Check this....
> http://msdn2.microsoft.com/library/e59b22c5.aspx
>
> Willy.
>
>
>

"Al the programmer" <(E-Mail Removed)> wrote in
message news:66BAFFCC-886E-435D-BC81-(E-Mail Removed)...
> Thanks for the info. The docs don't talk about importing a class, only
> functions, but I know where to start looking in the future. For my
> current
> project I need to access C functions, which I can do.
>
> Al
>

It doesn't talk about importing a class because it isn't possible to access
unmanaged classes cross-language.
If you need this, your only option is to create a wrapper class using
managed C++ (or better the upcoming C++/CLI)., this wrapper simply delegates
the accesses from managed code into unmanaged C++.

Willy.