Imports System.Text.RegularExpressions
Imports System.Text.Encoding
Imports System.Net

Public Class Form1

  Dim strHtmlText As String

  Function ReadHTML(ByVal url As String) As String
    Try
      Cursor = Cursors.WaitCursor
      Label1.Text = "Bitte warten...!"
      Label1.Refresh()

      Dim wc As New WebClient
      Dim res As String = UTF8.GetString(wc.DownloadData(url))
      Cursor = Cursors.Default
      Return res
    Catch ex As WebException
      Label1.Text = "Verbindungsfehler!"
      Label1.Refresh()
      lstLinkList.Items.Clear()
      MessageBox.Show(ex.Message, "Fehler bei der Verbindung", _
         MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
      Cursor = Cursors.Default
      Return ""
    End Try
  End Function

  Sub FindHrefs(ByVal inputString As String)
    Dim r As Regex
    Dim m As Match
    Dim regString As String = _
        "href\s*=\s*(?:""(?<1>[^""]*)""|(?<1>\S+))"

    r = New Regex(regString, _
        RegexOptions.IgnoreCase Or RegexOptions.Compiled)
    m = r.Match(inputString)
    lstLinkList.Items.Clear()

    While m.Success
      If m.Groups(1).Value.StartsWith("http") Then
        lstLinkList.Items.Add(m.Groups(1).Value) '& " an Pos.: " _
           & m.Groups(1).Index.ToString())
      End If
      m = m.NextMatch()
    End While

    Label1.Text = "Gefunden: " & lstLinkList.Items.Count.ToString
  End Sub

  Private Sub btnFind_Click(ByVal sender As System.Object, _
      ByVal e As System.EventArgs) Handles btnFind.Click
    strHtmlText = ReadHTML(TextBox1.Text)
    If strHtmlText <> "" Then
      FindHrefs(strHtmlText)
    End If
  End Sub

End Class