How do I write this VB6 dll call in C#? [RESOLVED]

[BrianHawley]

How do I call a legacy 32-bit dll from C#?

The VB6 code would look like this:

Option Explicit
 
Private Declare Function MyFunc Lib "my.dll" _
          (ByVal cmd As String) As Boolean
 
Private Sub Command1_Click()
  
  If MyFunc("abc") Then
    MsgBox "Cool!"
  End If
 
End Sub

How should that look in C#?

Thanks!

[axion_sa]

http://msdn.microsoft.com/library/de...rfExternPG.asp

class SomethingOrOther
{
    [DllImport("my.Dll")]
    public static extern bool MyFunc(string cmd);

    private void btnBlah_Click(object sender, EventArgs e)
    {
        if (MyFunc("abc"))
        {
            // Etc etc
        }
    }
}

[BrianHawley]

Many thanks!

[talktodale]

Please help: I did this example verbatim except for my path statement and I got the following erro:

Unable to find an entry point named 'MyFunc' in DLL 'c:\MyFunction32\my.Dll'.

Any ideas ?

[abhijit]

Please help: I did this example verbatim except for my path statement and I got the following erro:

Unable to find an entry point named 'MyFunc' in DLL 'c:\MyFunction32\my.Dll'.

Any ideas ?

Do you have the code for my.dll?
The DLLImport directive works with DLL's that have exported functions.

These attributes explicitly define the DLL's interface to its client, which can be the executable file or another DLL. Declaring functions as dllexport eliminates the need for a module-definition (.DEF) file, at least with respect to the specification of exported functions. Note that dllexport replaces the __export keyword.

If a class is marked declspec(dllexport), any specializations of class templates in the class hierarchy are implicitly marked as declspec(dllexport). This means templates are explicitly instantiated and its members must be defined.

dllexport of a C++ function will expose the function with C++ name mangling. If C++ name mangling is not desired, either use a .def file (EXPORTS keyword) or declare the function as extern "C".