Using a C# dll inside EXCEL VBA

问题:

I am running into a little problem here and need you guys' help.

I have a C# DLL exposed through COM interop. It is working alright, but apparently the deployment of C# interop object is a disaster and you need to regasm every time you update the DLL.

So I am wondering how I can use the functions from this C# DLL like the following: Or anything that I can call the functions by just putting the DLL and the spreadsheet together.

Declare Function getString Lib "" () as string  sub test()    range("A1").value = getString End Sub 

Syntax might be wrong.

回答1:

You can do that, but you have to be aware of the differences of VBA and .Net.
First, you have to create an actual DLL (.Net assemblies are not), to do that, use this project template. Then again, you have to be aware of how to marshal stuff.
VBA only supports stdcall as calling convention and it can't really deal with Unicode for DLL functions. This isn't bad per se, as the default marshaling for String in .Net is what VBA is expecting (a pointer to an Ansi char). Also, stdcall is the default calling convention that I use for exports.

I'll reuse a sample I've create recently for another SO thread:

Put this in a project you created using my template:

[ComVisible(true), ClassInterface(ClassInterfaceType.AutoDual)] public class Sample {    public string Text    {       [return: MarshalAs(UnmanagedType.BStr)]       get;       [param: MarshalAs(UnmanagedType.BStr)]       set;    }     [return: MarshalAs(UnmanagedType.BStr)]    public string TestMethod()    {       return Text + "...";    } }  static class UnmanagedExports {    [DllExport]    [return: MarshalAs(UnmanagedType.IDispatch)]    static Object CreateDotNetObject(String text)    {       return new Sample { Text = text };    } } 

This is how to call it from VBA:

Declare Function CreateDotNetObject Lib "The full path to your assembly or just the assembly if it is accessible from Excel" _   (ByVal text As String) As Object  Sub test()    Dim instance As Object    Set instance = CreateDotNetObject("Test 1")   Debug.Print instance.Text    Debug.Print instance.TestMethod    instance.text = "abc 123" ' case insensitivity in VBA works as expected'    Debug.Print instance.Text End Sub 

回答2:

i had this issue many times. i ended up registering the com dll from vba using a shell and wait method, on the regasm util to register/unregister the dll before late bound creating the com object via

 CreateObject('yourclasshere') 

Its a bit of a hack but it works, heres the shellandwait method and a register and unregister method that follows.

             Private Declare Function OpenProcess Lib "kernel32" _              (ByVal dwDesiredAccess As Long, ByVal bInheritHandle As Long, _              ByVal dwProcessId As Long) As Long               Private Declare Function GetExitCodeProcess Lib "kernel32" _              (ByVal hProcess As Long, lpExitCode As Long) As Long               Private Const STATUS_PENDING = &H103&              Private Const PROCESS_QUERY_INFORMATION = &H400                Private Function ShellandWait(ExeFullPath As String, _              Optional TimeOutValue As Long = 0) As Boolean                   Dim lInst As Long                  Dim lStart As Long                  Dim lTimeToQuit As Long                  Dim sExeName As String                  Dim lProcessId As Long                  Dim lExitCode As Long                  Dim bPastMidnight As Boolean                   On Error GoTo ErrorHandler                  lStart = CLng(Timer)                  sExeName = ExeFullPath                   'Deal with timeout being reset at Midnight                  If TimeOutValue > 0 Then                      If lStart + TimeOutValue  lTimeToQuit Then                          If bPastMidnight Then                               If Timer 

Hope it helps :)

回答3:

These are the using statements to put at the top of your class which are key:

using System.Diagnostics; using RGiesecke.DllExport;

Also ensure that you have a project started before the Nuget PM statement to install the template above. I am new at this - I am sure there are others as well. I am using AutoCAD VBA and got another error since it is 64 bit - I had to use PtrSafe (etc) in the Declare statement for VBA to continue without errors (see MS docs for this http://support.microsoft.com/kb/983043)

It worked btw!

My final code (based on the above)

using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Runtime.InteropServices; using System.Diagnostics; using RGiesecke.DllExport;  namespace ClassLibrary3 {     [ComVisible(true), ClassInterface(ClassInterfaceType.AutoDual)]     public class Class1     {         public string Text         {             [return: MarshalAs(UnmanagedType.BStr)]             get;             [param: MarshalAs(UnmanagedType.BStr)]             set;         }          [return: MarshalAs(UnmanagedType.BStr)]         public string TestMethod()         {             return Text + "...";         }     }      static class UnmanagedExports     {         [DllExport]         [return: MarshalAs(UnmanagedType.IDispatch)]         static Object CreateDotNetObject(String text)         {             return new Class1 { Text = text };         }     } } 

and my vba code:

#If VBA7 Then     Private Declare PtrSafe Function CreateDotNetObject Lib "G:\gitRepository\VS\ClassLibrary3\ClassLibrary3\bin\Debug\ClassLibrary3.dll" (ByVal text As String) As Object #Else     Private Declare Function CreateDotNetObject Lib "G:\gitRepository\VS\ClassLibrary3\ClassLibrary3\bin\Debug\ClassLibrary3.dll" (ByVal text As String) As Object #End If  Sub test()    Dim instance As Object    Set instance = CreateDotNetObject("Test 1")   Debug.Print instance.text    Debug.Print instance.TestMethod    instance.text = "abc 123" ' case insensitivity in VBA works as expected'    Debug.Print instance.text End Sub 

文章来源: Using a C# dll inside EXCEL VBA