Dim s As String = Me.RichTextBox1.Text.Trim '// Der Text
Dim hex As Integer
Dim ttmp, t As StringCount
Dim r As System.Text.RegularExpressions.Regex
Dim arr As ArrayList = New ArrayList
Dim arrt As ArrayList = New ArrayList
Dim ElapsedTime As TimeSpan
Dim StartTime As TimeSpan = New TimeSpan(Now.Ticks)
t = New StringCount(0, 0)
If (Not (s.Length Mod 2) = 0) Then s = s.Remove(s.Length - 1, 1)
For a As Integer = 0 To s.Length - 1 Step 2
  hex = Integer.Parse(s.Substring(a, 2), Globalization.NumberStyles.HexNumber)
  If Not arr.Contains(hex) Then
    arr.Add(hex)
    r = New System.Text.RegularExpressions.Regex(hex.ToString("X2"))
    ttmp = New StringCount(hex, r.Matches(s).Count)
    If ttmp.Count >= t.Count Then t = New StringCount(ttmp.Hex, ttmp.Count)
    arrt.Add(ttmp)
  End If
Next
ElapsedTime = New TimeSpan(Now.Ticks)
Me.Label1.Text = String.Format("Benötiget Zeit: {0} s {1} ms für {2} Zeichen", _
  ElapsedTime.Subtract(StartTime).Seconds, ElapsedTime.Subtract( _
  StartTime).Milliseconds, s.Length)
arrt.Sort()
Me.ListBox1.Items.Clear()
Me.ListBox1.Items.AddRange(arrt.ToArray(GetType(StringCount)))
MessageBox.Show(String.Format("{0} kommt {1} vor!", t.Hex.ToString("X2"), _
  t.Count)) '// Meist verwendetes Zeichen.
 
Public Class StringCount
    Implements IComparable
    Public Hex As Integer
    Public Count As Integer
    Public Sub New(ByVal Hex As Integer, ByVal Count As Integer)
        Me.Hex = Hex
        Me.Count = Count
    End Sub
    Public Overrides Function ToString() As String
        Return String.Format("String: {0:X2} Count: {1}", Me.Hex, Me.Count)
    End Function
    Public Function CompareTo(ByVal obj As Object) As Integer Implements _
      System.IComparable.CompareTo
        Select Case CType(obj, StringCount).Count
            Case Is = Me.Count : Return 0
            Case Is < Me.Count : Return -1
            Case Is > Me.Count : Return 1
        End Select
    End Function
End Class