'Beispiel: VB .Net - Nur Zahlen und Buchstaben in TextBox als gültige Eingabe auswerten 'Hinweis : Die Zeichenlänge muß eine min. Länge von 10 Zeichen aufweisen. ' Imports System Imports System.Drawing Imports System.Windows.Forms Imports System.Text.RegularExpressions 'Mehr Info zu RegularExpressions: 'http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemtextregularexpressions.asp Namespace DotNet_Zeichenüberprüfung Public Class MainForm Inherits System.Windows.Forms.Form Private button1 As System.Windows.Forms.Button Private textBox1 As System.Windows.Forms.TextBox Public Shared Sub Main Dim fMainForm As New MainForm fMainForm.ShowDialog() End Sub Public Sub New() MyBase.New Me.InitializeComponent End Sub #Region " Windows Forms Designer generated code " Private Sub InitializeComponent() Me.textBox1 = New System.Windows.Forms.TextBox Me.button1 = New System.Windows.Forms.Button Me.SuspendLayout ' 'textBox1 ' Me.textBox1.Location = New System.Drawing.Point(8, 8) Me.textBox1.Name = "textBox1" Me.textBox1.Size = New System.Drawing.Size(272, 20) Me.textBox1.TabIndex = 1 Me.textBox1.Text = "textBox1" ' 'button1 ' Me.button1.Location = New System.Drawing.Point(72, 80) Me.button1.Name = "button1" Me.button1.Size = New System.Drawing.Size(152, 24) Me.button1.TabIndex = 0 Me.button1.Text = "&Test..." AddHandler Me.button1.Click, AddressOf Me.Button1Click ' 'MainForm ' Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13) Me.ClientSize = New System.Drawing.Size(292, 109) Me.Controls.Add(Me.textBox1) Me.Controls.Add(Me.button1) Me.MaximizeBox = false Me.MinimizeBox = false Me.Name = "MainForm" Me.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen Me.Text = "Testform <Textbox auf bestimmte Zeichen überprüfen...>" AddHandler Load, AddressOf Me.MainFormLoad Me.ResumeLayout(false) End Sub #End Region Private Function IsValidInput(tb As TextBox) As Boolean 'Nur Zahlen und Buchstaben sind zugelassen in einer min. Länge von 10 Zeichen Const BadIndications As String = "^\s*(\w){10}\s*$" 'Mehr Infos zu RegEx: 'http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemtextregularexpressionsregexclasstopic.asp If Not RegEx.IsMatch(tb.Text, BadIndications) Then MessageBox.Show("Falsche Eingabe. Geben Sie mindestens 10 Zeichen (Buchstaben und Zahlen) ein!", "Info", MessageBoxButtons.OK, MessageBoxIcon.Information) Return False End If Return True End Function Private Sub Button1Click(sender As System.Object, e As System.EventArgs) Dim blResult As Boolean blResult = IsValidInput(textBox1) If blResult Then MessageBox.Show(blResult.ToString & " Eingabe Ok") End If End Sub Private Sub MainFormLoad(sender As System.Object, e As System.EventArgs) textBox1.Text = "Hallo-Welt" End Sub End Class End Namespace