MaskedTextBox

This accepts text input of a specific format. We often require phone numbers to have their area code and also the correct number of digits.

To solve this problem, we use the MaskedTextBox control in Windows Forms. We can provide hints about what mistake caused the rejection.

Start

Please add a MaskedTextBox control to your Windows Forms program. Next, try changing the properties of the MaskedTextBox by right-clicking on it and selecting properties.

using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void maskedTextBox1_MaskInputRejected(object sender,
            MaskInputRejectedEventArgs e)
        {
            // Set the window title text
            // ... to the MaskInputRejectedEventArgs information.
            this.Text = "Error: " +
                e.RejectionHint.ToString() +
                "; position: " +
                e.Position.ToString();
        }
    }
}

Validation

The MaskedTextBox can convert the input into a C# type. In this example, we set the format to the "Short date" mask pattern.

using System;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void maskedTextBox1_TypeValidationCompleted(object sender,
            TypeValidationEventArgs e)
        {
            // This event is raised when the enclosing window is closed.
            // ... We show a MessageBox that details the DateTime.
            DateTime value = (DateTime)e.ReturnValue;
            MessageBox.Show("Validated: " + value.ToLongDateString());
        }
    }
}

AsciiOnly

The AsciiOnly property enforces that every character entered not be an accented or Unicode-only character. This is useful when you require strict data input.

CutCopyMaskFormat

This property lets you adjust how the text will be copied. It specifies whether the separators are included in the copied text.

PasswordChar and PromptChar

The MaskedTextBox lets you change the character that appears when a password is entered. By default, the prompt character is an underscore "_".

ResetOnPrompt and ResetOnSpace

These two properties are usability features. When you have a mask, there will be some prompt characters such as the "/" or "_" values.

The MaskedTextBox control in Windows Forms enforces the range of input that is allowed into the text box. It is ideal for when you want to collect data like phone numbers.