Imports System

Imports Microsoft.VisualBasic

​

Public Module Module1

    Public Sub Main()

        Dim didItWork as Boolean = False

        Dim myTestObject as Test = Nothing

        ' works, due to IF(). Only the 'true' value is calculated

        didItWork = If(myTestObject Is Nothing, False, myTestObject.MyValue)

            Console.WriteLine("Did If() work?: " & didItWork.ToString())

            ' does not work, due to IIF().  Both True and False conditions are calculated regardless of the original test condition.

            '  it fails because myTestObject is null, so trying to access one of its properties causes an exception.

            Try

                didItWork = IIF(myTestObject Is Nothing, False, myTestObject.MyValue)

                Console.WriteLine("Did IIF() work?: " & didItWork.ToString())

            Catch ex as Exception

                Console.WriteLIne("Error was thrown from IIF")

            End Try

    End Sub

End Module

​

    Public Class Test

        Public Property MyValue as Boolean = True

End class