Option Strict On

Module Module1
    Sub Main()
        Dim i As New Complex(0, 1)
        If i Then MsgBox("i")
    End Sub
End Module

Module Module2
    Sub Main()
        Dim c As Collection
        ' In VB6:
        If Not c Is Nothing Then
            If c.Count > 0 Then
                ' ...
            End If
        End If

        ' In VB.NET/2005:
        If c IsNot Nothing AndAlso c.Count > 0 Then
            ' ...
        End If
    End Sub
End Module

Module Module3
    Sub Main()
        Dim i As New Complex(0, 1)
        Dim j As New Complex(1, 0)
        If i AndAlso j Then
            ' ...
        End If
    End Sub
End Module

' Definition of a class for complex numbers with double precision
Structure Complex
    Public Re As Double
    Public Im As Double

    Public Sub New(ByVal re As Double, ByVal im As Double)
        Me.Re = re : Me.Im = im
    End Sub

    Public Shared Operator +(ByVal lhs As Complex, ByVal rhs As Complex) As Complex
        Return New Complex(lhs.Re + rhs.Re, lhs.Im + rhs.Im)
    End Operator

    ' ...
End Structure

' Boolean conversion
Partial Structure Complex
    Public Shared Widening Operator CType(ByVal rhs As Complex) As Boolean
        Return rhs.Re <> 0 OrElse rhs.Im <> 0
    End Operator
End Structure

' Operators for short-circuiting
Partial Structure Complex
    Public Shared Operator Not(ByVal rhs As Complex) As Boolean
        Return rhs.Re = 0 AndAlso rhs.Im = 0
    End Operator

    Public Shared Operator IsFalse(ByVal rhs As Complex) As Boolean
        Return Not rhs
    End Operator

    Public Shared Operator IsTrue(ByVal rhs As Complex) As Boolean
        Return rhs
    End Operator
End Structure