Challenge 9 (VB.NET)

Module Module1
    Sub Main()
        Dim file_name As String = "challenge9_list.txt"
        Dim f As New IO.StreamReader(file_name)
        Dim ch As Char
        Dim sumdigit As UInt16 = 0
        Dim alpha() As UInt16 = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}

        While Not f.EndOfStream
            ch = f.ReadLine()(0)
            If Char.IsDigit(ch) Then
                sumdigit += Convert.ToInt16(ch)
            ElseIf Char.IsLetter(ch) Then
                alpha(Asc(ch) - Asc("a"c)) += 1
            End If
        End While

        Console.WriteLine("Sum = {0}", sumdigit)
        For i As UInt16 = 0 To alpha.Length - 1
            If alpha(i) <> 0 Then
                Console.WriteLine("'{0}' = {1}", Chr(i + Asc("a"c)), alpha(i))
            End If
        Next

        Console.ReadKey(True)
    End Sub
End Module