Walkthrough: Working with the MaskedTextBox Control

Tasks illustrated in this walkthrough include:

• Initializing the MaskedTextBox control

• Using the MaskInputRejected event handler to alert the user when a character does not conform to the mask

• Assigning a type to the ValidatingType property and using the TypeValidationCompleted event handler to alert the user when the value they're attempting to commit is not valid for the type

For a full working version of the MaskedTextBox control that demonstrates advanced features such as validation using custom data types, see MaskedTextBox Control Sample.

Creating the Project and Adding a Control

To add a MaskedTextBox control to your form

1. Open the form on which you want to place the MaskedTextBox control.

2. Drag a MaskedTextBox control from the Toolbox to your form.

3. Right-click the control and choose Properties. In the Properties window, select the Mask property and click the ... (ellipsis) button next to the property name.

4. In the Input Mask dialog box, select the Short Date mask and click OK.

5. In the Properties window set the BeepOnError property to true. This property causes a short beep to sound every time the user attempts to input a character that violates the mask definition.

Alert the User to Input Errors

Add a balloon tip for rejected mask input

1. Return to the Toolbox and add a ToolTip to your form.

2. Create an event handler for the MaskInputRejected event that raises the ToolTip when an input error occurs. The balloon tip remains visible for five seconds, or until the user clicks it.

   public void Form1_Load(Object sender, EventArgs e) 
   {
       ... // Other initialization code
       maskedTextBox1.Mask = "00/00/0000";
       maskedTextBox1.MaskInputRejected += new MaskInputRejectedEventHandler(maskedTextBox1_MaskInputRejected)
   }
   
   void maskedTextBox1_MaskInputRejected(object sender, MaskInputRejectedEventArgs e)
   {
       toolTip1.ToolTipTitle = "Invalid Input";
       toolTip1.Show("We're sorry, but only digits (0-9) are allowed in dates.", maskedTextBox1, maskedTextBox1.Location, 5000);
   }
   

   Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
       Me.ToolTip1.IsBalloon = True
       Me.MaskedTextBox1.Mask = "00/00/0000"
   End Sub
   
   Private Sub MaskedTextBox1_MaskInputRejected(sender as Object, e as MaskInputRejectedEventArgs) Handles MaskedTextBox1.MaskInputRejected
       ToolTip1.ToolTipTitle = "Invalid Input"
       ToolTip1.Show("We're sorry, but only digits (0-9) are allowed in dates.", MaskedTextBox1, 5000)
   End Sub
   

Alert the User to a Type that Is Not Valid

Add a balloon tip for invalid data types

1. In your form's Load event handler, assign a Type object representing the DateTime type to the MaskedTextBox control's ValidatingType property:

   private void Form1_Load(Object sender, EventArgs e)
   {
       // Other code
       maskedTextBox1.ValidatingType = typeof(System.DateTime);
       maskedTextBox1.TypeValidationCompleted += new TypeValidationEventHandler(maskedTextBox1_TypeValidationCompleted);
   }
   

   Private Sub Form1_Load(sender as Object, e as EventArgs)
       // Other code
       MaskedTextBox1.ValidatingType = GetType(System.DateTime)
   End Sub
   

2. Add an event handler for the TypeValidationCompleted event:

   public void maskedTextBox1_TypeValidationCompleted(object sender, TypeValidationEventArgs e)
   {
       if (!e.IsValidInput)
       {
          toolTip1.ToolTipTitle = "Invalid Date Value";
          toolTip1.Show("We're sorry, but the value you entered is not a valid date. Please change the value.", maskedTextBox1, 5000);
          e.Cancel = true;
       }
   }
   

   Public Sub MaskedTextBox1_TypeValidationCompleted(sender as Object, e as TypeValidationEventArgs)
       If Not e.IsValidInput Then
          ToolTip1.ToolTipTitle = "Invalid Date Value"
          ToolTip1.Show("We're sorry, but the value you entered is not a valid date. Please change the value.", maskedTextBox1, 5000)
          e.Cancel = True
       End If
   End Sub
   

See Also

Reference

MaskedTextBox

Other Resources

MaskedTextBox Control (Windows Forms)