QTP - Calling C# DLL in VBScript

A while ago I wanted to call a C# dll from a QTP script.  I posted my question here on stackoverflow.

 Short Explanation

• Create a C# dll using Visual Studio.
• Use the DotNetFactory in QTP to call the public methods in the C# dll.

Step 1 - Create a C# DLL

 Create Visual Studio Solution and Project

• Start Visual Studio 2010
• File > New > Project
• .NET Framework 3.5
• Visual Studio > Windows > Class Library
• Name = mydll
• Location = c:\
• Solution name = ClassLibrary
• OK

 Create Public Method

• Rename Class1.cs to functions.cs. Yes to rename all references.
• Create a public method: public int GetValue() { return 34; }

 Build DLL

• Save
• Build > Build Solution
• Look in C:\ClassLibrary\mydll\bin\Debug (or Release) for the mydll.dll
• Close Visual Studio 2010

Step 2 - Create QTP Script

 Create QTP Script

• Start QTP
• File > New > Test
• Set obj = DotNetFactory.CreateInstance("mydll.functions", "c:\\classlibrary\\mydll\\bin\\debug\\mydll.dll")
• MsgBox "GetValue() from C# dll returns : " & obj.GetValue()

 Run QTP Script

• Run the script.
• Message box with '34' is displayed.