How To Pass a String Between and a C sharp DLL

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.
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Fernando SotoConnect With a Mentor RetiredCommented:
Hi Hagita;

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

Carl TawnSystems and Integration DeveloperCommented:
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.
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.
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HagitaAuthor Commented:
Fernando, Thank you so much for the code solution. I will use it and see if no problem arise.
Thaks alot!
Fernando SotoRetiredCommented:
Not a problem, glad to be of help.  ;=)
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.
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