Calling wrapped C++ DLL method from C#: passing addresses of integral variables to get output

Question

I need to call a wrapped function from a C++ DLL with the following declaration:

[DllImport(@dllPath, EntryPoint = "Calling_fooBar")]
private static extern int Calling_fooBar( uint*   a,
                                          uint*   b,
                                          uint*   c,
                                          uint*   d,
                                              //etc );

Used in this way:

private void getData()
{
    uint A, B, C, D; //etc
    Calling_fooBar( &A, &B, &C, &D );

    // ...
}

Upon doing this, A, B, C, D are all still 0. I'm quite sure the external method in the DLL is working properly so they should have non-zero values.
So I'm guessing I'm passing the address wrong ... or something.

Hopefully this isn't too dumb a question. I can clarify anything if needed

Answer 1

尝试将*和&更改为ref 。

Answer 2

Yes to Slaks above. Here's what my code which successfully does such things looks like:

[DllImport("blah.dll")]
private static extern int thingy( ref uint refArg );
/* ... later in the code. ...*/
int retVal = thingy( ref refVariable );