Menghitung jumlah Huruf Vokal

Module Module1

    Sub Main()
        Dim a As String
        Dim i, j, vokal As Integer
        Dim b() As String = {"a", "i", "u", "e", "o"}
        Dim tmp() As Char
        '--------------------------------

        Console.WriteLine()
        Console.WriteLine("Mencari Huruf Vocal")
        Console.WriteLine()
        Console.Write("Masukan String 1: ")
        a = Console.ReadLine()
        Console.WriteLine()
        ReDim tmp(Len(a))
        i = 1
        For i = 0 To (Len(a) - 1)
            For j = 0 To 4
                If Mid(a, (i + 1), 1) = b(j) Then
                    vokal = vokal + 1
                End If
            Next
        Next
        Console.Write("Jumlah huruf vokal : ")
        Console.Write(vokal)

        Console.ReadLine()

    End Sub

End Module