if vowellabel.substring(indexnum,1) = vowel then
mid(me.vowel.text) = vowel
replaceX = true
end if

Module Module1

    Sub Main()

        Dim myStr As String = "The answer is 42. Today is 6/17"

        Dim c As Char = ""
        Dim d As Char = ""

        Dim temp As String = ""

        For Each c In myStr
            d = ChangeIt(c)
            temp = String.Concat(temp, Convert.ToString(d))
        Next

        Console.WriteLine("Original: " + myStr)
        Console.WriteLine("Modified: " + temp)
        Console.WriteLine("done")
        myStr = Console.ReadLine()

    End Sub

    Public Function ChangeIt(ByVal c As Char) As Char

        Dim a As Char = ""
        Dim vowel As String = "aeiouy"

        If Char.IsDigit(c) Then
            Return "z"
        Else
            For Each a In vowel
                If Char.ToUpper(a) = Char.ToUpper(c) Then
                    Return "x"
                End If
            Next
        End If

        Return c

    End Function

End Module