The .NET languages interoperate with each other; that is, code of one language can be used from another after getting converted to IL. To test this create a new project in VB.Net with a template Class Library and name it vbproject.

By default the project comes with a class class1.

Write the following code in it

Public Class Class1

Public Function Add(ByVal x As Integer, ByVal y As Integer) As Integer
 Return x + y

End Function
Public Sub Hello(ByVal name As String)
Console.WriteLine("Hello" & name)
End Sub
End Class

As we can't execute the class we need to only compile it & convert it into an assembly. To do this open the solution explorer and right click on the project.

Select Build to build your project

Consuming the Class from C# programing-

Now create a new project in C#; name it Testvb and add a reference for the vb project assembly from its physical location which is in projects bin\Debug folders.
To add a reference follow following steps-
  1. Open solution explorer.
  2. Right Click on project .
  3. Click on Add reference..
  4. Click on Browse Button.
  5. Go to your project's physical path for example if your project name is myvb then assembly path will be C:\myvb\bin\Debug here you can find the assembly.
  6. Click the OK Button.

Here is a Screen shot which will help you to add a reference:

a.gif
a1.gif

Now write Following code under Testvb

Note: don't Forget to add a namspace using VbProject; which is our VB project name.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using VbProject;

namespace Testvb
{
class Program
 {
static void Main(string[] args)
{
Class1 obj = new Class1();
Console.WriteLine(obj.Add(20,30));
obj.Hello("Ankit");
Console.Read();
}
}
}

Now Run your Console Application .