I have been coding in VB.NET on contract for just under a year now. And having done so, I have come up with a small list of 'Gotchas' that I have encountered. At times, these differences have cost me quite a bit of time in debugging, and if I can save someone else even a small amount of this pain, it will be worth it.

VB.NET does not throw a compiler error when you create a function without a return type. Can you tell me the return type of the method below?

    Public Function GetNumberOne()

        Dim num As Integer = 1

        Return num

    End Function

VB.NET is also content compiling a Function without a return statement. It isn't frequent that I forget to add a return statement, but it has happened.

    Public Function WithoutReturnStatement() As Integer

        Dim bool = False

        Dim s = "A String"

        Dim concat = String.Concat(s, bool)

    End Function

Another good idea: turn on Option Strict. If you don't, the runtime will attempt to do a lot of implicit conversions for you. I wrote some code where I thought that I could call GetBoolean() on a DataReader passing in a string representing the column name. It compiled fine. After running the application, I realized that I needed to pass in the columns index instead. Sure, if I would have slowed down, Intellisense would have told me different, but I was cocky

    Public Sub TakesNumberParam(ByVal value As Integer)

        Dim result = value + 1

    End Sub

Without option explicit on, I am able to write a test for the above method, that passes in a string that cannot be cast to an integer, and the project builds. At runtime, the code will throw an InvalidCastException.