VB for C# Developers part 1

The last year I’ve been involved in a mixed project containing C# and VB.Net code. Switching between them was difficult at first for me as a C# developer. In this blog post I’ll explain some of the differences in syntax between C# and VB.Net.

Abstract

Abstract uses a little bit different keywords in vb as can be seen below:

Virtual methods

Virtual syntax is also a little bit different


Generics

Generics in VB are almost the same as in C# they only have a different syntax for declaring them because the of the way that VB handles them.

C#

List<SomeType> list = new List<SomeType>();

VB#

Dim  list As New List(Of SomeType)

The major difference is the round brackets in the syntax and the use of the Of keyboard that indicates that it is of a certain type.

Event Handlers

Event handler syntax is different than in C#. There a two methods of defining events in Vb. You can use the With Events or the Add/Remove Handler methods for that. Below I’ll give some examples of both:

Add/RemoveHandler

The VB equivalent of the += operator for events is using the Add/Remove handler methods in VB.

  • AddHandler

    This method is used to add a handler to a certain event. It takes the event as parameter and the a delegate that points to the specific method. This is done by using the AddressOf command.

     

  • RemoveHandler
    Just as adding a method is done by using the AddHandler removing one is done using RemoveHandler.

    WithEvents/Handles

The Syntax for withEvents/Handles is difficult to explain. Below I’ll give an explanation of the keywords and an code sample.

  • WithEvents

    WithEvents is used on a variable and indicates that the object that this variable hold can throw an event.

  • Handles

    The handles is used on a method and it indicates that this method is called when the event it registers to is triggered.

An Example of using WithEvents can be seen below:

In the above example I’ve created a Class “Test” with one public event named “TestEvent”

The large difference between the two methods is that when you use the WithEvents/Handles methods you’ll never know exactly when you’re eventhandlers will actually be added

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