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MaskedTextBox.MaskFull Property

Gets a value indicating whether all required and optional inputs have been entered into the input mask.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

public bool MaskFull { get; }

Property Value

Type: System.Boolean
true if all required and optional inputs have been entered; otherwise, false.

You can use the MaskFull property within the MaskInputRejected event handler to determine if the user's input was rejected because there are no remaining inputs in the mask. To determine whether only required input elements have been entered, use the MaskCompleted property.

The following code example handles the MaskInputRejected event, and uses a ToolTip to alert the user if an attempt is made to enter data after all positions in the mask have been used.

private void Form1_Load(object sender, EventArgs e)
    maskedTextBox1.Mask = "00/00/0000";

    maskedTextBox1.MaskInputRejected += new MaskInputRejectedEventHandler(maskedTextBox1_MaskInputRejected);
    maskedTextBox1.KeyDown += new KeyEventHandler(maskedTextBox1_KeyDown);

void maskedTextBox1_MaskInputRejected(object sender, MaskInputRejectedEventArgs e)
    if (maskedTextBox1.MaskFull)
        toolTip1.ToolTipTitle = "Input Rejected - Too Much Data";
        toolTip1.Show("You cannot enter any more data into the date field. Delete some characters in order to insert more data.", maskedTextBox1, 0, -20, 5000);
    else if (e.Position == maskedTextBox1.Mask.Length)
        toolTip1.ToolTipTitle = "Input Rejected - End of Field";
        toolTip1.Show("You cannot add extra characters to the end of this date field.", maskedTextBox1, 0, -20, 5000);
        toolTip1.ToolTipTitle = "Input Rejected";
        toolTip1.Show("You can only add numeric characters (0-9) into this date field.", maskedTextBox1, 0, -20, 5000);

void maskedTextBox1_KeyDown(object sender, KeyEventArgs e)
    // The balloon tip is visible for five seconds; if the user types any data before it disappears, collapse it ourselves.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.