Access return value from VBA Function in .NET?

问题

I have the following code in VBA (which resides in an Excel 2007 Workbook):

Public Function Multiply(a As Double, b As Double) As Double
    Multiply = a * b
End Function

If I invoke Multiply from other VBA code, it returns the correct value. However, when I call Multiply from C#:

var excel = new Application {Visible = true};
excel.Workbooks.Open(filename);
var returned = excel.Run("Sheet1.Multiply", (Double) a, (Double) b);

... the multiplication takes place (I can verify this by adding tracing to the Multiply function in VBA) but the returned value isn't available in my C# code; returned is always null.

Could someone please tell me how to get at the return value of Multiply from my C# code?

回答1:

Have you tried moving your function to a regular module in Excel (not a sheet module)?

回答2:

A simple example :

The test spreadsheet.xlsm has Module1 containing:

Public Function test() As String
  test = "hello 1234"
End Function

With objExcel already set to the spreadsheet...

Dim result = objExcel.Run("Module1.test")
MsgBox(result)

... produces hello 1234 in the pop-up message.

Because I had originally tested this with ? module1.test() (successfully) in the VBA Immediate window, I was initially trying to get objExcel.Run("Module1.test()") to work - but I was getting an error: Cannot run the macro .... The macro may not be available in this workbook or all macros may be disabled. - removing the brackets did the trick.

回答3:

Try modifying your Multiply function to be like the code below:

Public Function Multiply(a As Double, b As Double) As Double
    return a * b
End Function

来源：https://stackoverflow.com/questions/3920343/access-return-value-from-vba-function-in-net