How To Pass a String Between and a C sharp DLL

Posted on 2011-02-27
Last Modified: 2012-05-11
Hello Experts,
I am new to C sharp, I need to pass a string parameter from my project to a  c # dll . I have a code in c# application and need to convert to dll that can be used in my code.
I know it is a problem since  strings are handeled diffrently by both languages plus I have never written a dll in c#. can anyone make it clearer? asample code would be great.
Question by:Hagita
LVL 52

Expert Comment

by:Carl Tawn
ID: 34991601
It isn't a problem, and the two languages don't handle strings differently. C# and VB.Net are both CLR languages and therefore work the same way. You can pass a string from VB.Net to C# in exactly the same way as you would normally.
LVL 11

Expert Comment

ID: 34991679
As Carl_tawn said, Just if you refer your dll to your VB.Net project, create an object for the class and use it.


C# Project:

Public class CSharpTest
Public string HelloWorld(string psTest)
   return psTest;
Make this as dll

Add this dll as reference to your VB.Net project

In you code
Dim objCSharpTest As New CSharpTest
Dim sRetValue As String = objCSharpTest.HelloWorld("Accessed CSharp dll")

SRetValue should have string you passed.
LVL 63

Accepted Solution

Fernando Soto earned 500 total points
ID: 34991985
Hi Hagita;

You can download this small solution which implements a C# dll in a VB .Net project to use as a template

Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.


Author Comment

ID: 34994727
Fernando, Thank you so much for the code solution. I will use it and see if no problem arise.
Thaks alot!
LVL 63

Expert Comment

by:Fernando Soto
ID: 34996513
Not a problem, glad to be of help.  ;=)

Expert Comment

ID: 34996739
A C# and a VB.NET dll are the same except for debugging information

When mixing VB.NET and C# code you should take following things into consideration:

1) VB.NET supports optional parameters, but C# does not (except C# 4.0). If you want to call a VB.NET method from C# you must provide all parameters and must know the default values. If you use them excessively this can be a pain.

2) C# is case sensitive, but VB.NET is not. Avoid any situations where you have to members with the same name, but only different casing. On the other side if you call VB.NET functions with strange casing rules from C# it can also be a problem. If you change casing in VB.NET code this will not break anything. In the C# code accessing it, it will create syntax errors or in some situations create other meaning. Example:

Dim openFileDialog as New OpenFileDialog
OpenFileDialog.Show() 'Accesses the instance members of the class.

OpenFileDialog openFileDialog = new OpenFileDialog();
OpenFileDialog.Show(); //Accesses the shared members of the class => syntax error

3.) In VB.NET you can access shared members of a class through and instance. If C# you cant do that. This does not break code, but it can have strange effects when translating code.

4.) C# has static classes. VB.NET only has Modules, but this is not the same. Maybe you can run into trouble here.

5) For debugging a C# dll behaves like a VB.NET dll if you use Visual Studio Standard or higher. You can debug your C# dll line by line directly from your VB.NET project like you would do with a VB.NET dll, can edit the code with limited syntax highlighting, but for recompiling it you have to open your C# dll project.

6) If you use the Express edition you have to install both editions and must choose which version you use to open your solution.

Featured Post

Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
RLDC Reporting in Visual studio 11 28
Sending receiving text messages in 15 47
Iteration Help ( VB) 5 24
Very Large data in MYSQL 7 73
This tutorial is posted by Aaron Wojnowski, administrator at  To view more iPhone tutorials, visit This is a very simple tutorial on finding the user's current location easily. In this tutorial, you will learn ho…
Windows programmers of the C/C++ variety, how many of you realise that since Window 9x Microsoft has been lying to you about what constitutes Unicode ( They will have you believe that Unicode requires you to use…
The goal of this video is to provide viewers with basic examples to understand and use pointers in the C programming language.
Video by: Grant
The goal of this video is to provide viewers with basic examples to understand and use nested-loops in the C programming language.

789 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question