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How to call a .NET DLL from a VBScript

, 12 Oct 2010 CPOL
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You might be wondering how you can call a .NET DLL from a VB Script. Well, look no further, as I will explain how to achieve this in a step by step manner.

You might be wondering how you can call a .NET DLL from a VB Script. Well, look no further, as I will explain how to achieve this in a step by step manner.

You might be wondering why you want to do this?

Why not just do everything in .NET or VBScript?

Well there might be some instances where this will be useful, like modifying a start-up script for GPO which is already in VBScript, but you want to extend it safely (compiled codes) or just reuse available DLLs that are out there in your organization saving you time to redevelop the same thing again. There are a lot of reasons that you want to do this but this is why I am doing it, unless someone else suggests a better way of doing it. Anyways I am writing this so that if anyone needs this reference, it's just here.

Ok let's start with what you need. Definitely you need to develop or use an existing DLL. For this example, we will develop it from scratch, you also need the VBScript that you want to edit or create and that’s it.

Step 1: Your DLL. Fire up Visual Studio you can develop either in C#, VB or any language you want, this sample will be C#. You need to create a Class Library Project.

using System;
using System.Runtime.InteropServices;
namespace MyDLL
 public class Operations
 public string getValue1(string sParameter)
 switch (sParameter)
 case "a":
 return "A was chosen";

 case "b":
 return "B was chosen";

 case "c":
 return "C was chosen";

 return "Other";
 public string getValue2()
 return "From VBS String Function";

In the code above, apply the ComVisibleAttribute Class controls accessibility of an individual managed type or member, or of all types within an assembly, to COM. You can apply this attribute to classes, structures, interfaces, delegates, enumerations, fields, methods, assemblies or properties. By default, it is set to true but in case you want to hide the individual type, you can just set it to false (I just showed it for reference purposes, as you notice the getValue2 does not have that attribute, but still it is visible).

Build the project.

Now after creating this Class Library Project, you have to configure it so that when you compile it will register on the systems assembly. There are two ways of doing that; one is to a command prompt. If you have .NET Framework 2.0 installed, regasm would be in the following path at:


And use the following for registering and unregistering an assembly:

Register assembly manually

The one on top registers it and the one at the bottom unregisters it. Now what does that the /codebase option stand for? You need to use the /codebase switch when you don’t have your assembly in GAC because that will add an absolute path for your assembly in registry so that COM client can find it.

Another option is Directly to Visual Studio, this is the easy way and it’s as easy as ticking a check box in the project properties.

Register assembly

Now you have your DLL ready.

Step 2: Create your VBScript and here is my sample:

dim myObj
Dim myClass
Set myObj = CreateObject("MyDLL.Operations")
MsgBox myObj.getValue1("a")
MsgBox myObj.getValue2()

Now run your VBScript and that’s it.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Raymund Macaalay
Technical Lead
New Zealand New Zealand
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Comments and Discussions

QuestionCalling .Net Dll (Default Property) from VBScript PinmemberVinoth_KT5-Dec-13 1:59 
Questionref. How to call a .NET DLL from a VBScript PinmemberMember 1001963830-Apr-13 1:19 
QuestionHow to call a VBScript's function from a .NET DLL? PinmemberMember 97380557-Jan-13 22:58 
QuestionHow to call a .NET DLL from a VBScript PinmemberMember 25560031-Oct-12 3:52 
AnswerRe: How to call a .NET DLL from a VBScript PinmemberTL1000S4-Oct-12 4:28 
Questionactivex component can't create object PinmemberMember 928428820-Jul-12 10:25 
i've tried this example but the vbscript fails with an error that activex component can't create object. i also tried following the modified example in the comments. used regasm. any thoughts on what i'm doing wrong. used vs2010 for creating example. running on a windows 7 64bit box.
AnswerRe: activex component can't create object PinmemberMember 945127417-Mar-14 7:10 
GeneralGood Article PinmemberIrwan Hassan19-Oct-10 20:45 
GeneralRe: Good Article PinmemberRaymund Macaalay19-Oct-10 23:53 
GeneralNice One PinmemberAnurag Gandhi18-Oct-10 21:51 
GeneralImproovements for your code PinmemberReinhard Ostermeier13-Oct-10 6:11 
GeneralRe: Improovements for your code PinmemberRaymund Macaalay13-Oct-10 10:18 
GeneralIntellisense PinmemberJohan197416-Jul-10 1:22 
GeneralRe: Intellisense PinmemberRaymund Macaalay17-Jul-10 22:50 
Questionother types? Pinmemberpeterbacsi10-May-10 23:24 
AnswerRe: other types? PinmemberRaymund Macaalay11-May-10 0:06 
GeneralThanks a lot PinmemberIrwan Hassan10-May-10 18:29 
GeneralNice! PinmemberMatt McKinney6-May-10 8:29 

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