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MaskedTextBox.Mask Property

Gets or sets the input mask to use at run time.

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

public string Mask { get; set; }

Property Value

Type: System.String
A String representing the current mask. The default value is the empty string which allows any input.

ExceptionCondition
ArgumentException

The string supplied to the Mask property is not a valid mask. Invalid masks include masks containing non-printable characters.

Mask is the default property for the MaskedTextBox class.

Mask must be a string composed of one or more of the masking elements, as shown in the following table. The masking language used by MaskedTextBox is defined by its associated MaskedTextProvider. The standard provider specifies a masking language based upon the one used by the Masked Edit control in Visual Basic 6.0, and should be very familiar to users migrating from that platform.

Masking element

Description

0

Digit, required. This element will accept any single digit between 0 and 9.

9

Digit or space, optional.

#

Digit or space, optional. If this position is blank in the mask, it will be rendered as a space in the Text property. Plus (+) and minus (-) signs are allowed.

L

Letter, required. Restricts input to the ASCII letters a-z and A-Z. This mask element is equivalent to [a-zA-Z] in regular expressions.

?

Letter, optional. Restricts input to the ASCII letters a-z and A-Z. This mask element is equivalent to [a-zA-Z]? in regular expressions.

&

Character, required. If the AsciiOnly property is set to true, this element behaves like the "L" element.

C

Character, optional. Any non-control character. If the AsciiOnly property is set to true, this element behaves like the "?" element.

A

Alphanumeric, required. If the AsciiOnly property is set to true, the only characters it will accept are the ASCII letters a-z and A-Z. This mask element behaves like the "a" element.

a

Alphanumeric, optional. If the AsciiOnly property is set to true, the only characters it will accept are the ASCII letters a-z and A-Z. This mask element behaves like the "A" element.

.

Decimal placeholder. The actual display character used will be the decimal symbol appropriate to the format provider, as determined by the control's FormatProvider property.

,

Thousands placeholder. The actual display character used will be the thousands placeholder appropriate to the format provider, as determined by the control's FormatProvider property.

:

Time separator. The actual display character used will be the time symbol appropriate to the format provider, as determined by the control's FormatProvider property.

/

Date separator. The actual display character used will be the date symbol appropriate to the format provider, as determined by the control's FormatProvider property.

$

Currency symbol. The actual character displayed will be the currency symbol appropriate to the format provider, as determined by the control's FormatProvider property.

<

Shift down. Converts all characters that follow to lowercase.

>

Shift up. Converts all characters that follow to uppercase.

|

Disable a previous shift up or shift down.

\

Escape. Escapes a mask character, turning it into a literal. "\\" is the escape sequence for a backslash.

All other characters

Literals. All non-mask elements will appear as themselves within MaskedTextBox. Literals always occupy a static position in the mask at run time, and cannot be moved or deleted by the user.

If you change a mask when MaskedTextBox already contains user input filtered by a previous mask, MaskedTextBox will attempt to migrate that input into the new mask definition. If it fails, it will clear the existing input. Assigning a zero-length string as the mask will preserve any existing data in the control. When used with a zero-length mask, MaskedTextBox behaves like a single-line TextBox control.

The decimal (.), thousandths (,), time (:), date (/), and currency ($) symbols default to displaying those symbols as defined by the application's culture. You can force them to display symbols for another culture by using the FormatProvider property.

Character insertion into the mask at run time is controlled by the InsertKeyMode property. Users can navigate through the mask by using the left and right arrow keys or the mouse cursor, and can skip optional positions in the mask by entering a space.

Important noteImportant

MaskedTextBox supports all Unicode characters except for surrogates and vertically combined characters.

The following table shows example masks.

Mask

Behavior

00/00/0000

A date (day, numeric month, year) in international date format. The "/" character is a logical date separator, and will appear to the user as the date separator appropriate to the application's current culture.

00->L<LL-0000

A date (day, month abbreviation, and year) in United States format in which the three-letter month abbreviation is displayed with an initial uppercase letter followed by two lowercase letters.

(999)-000-0000

United States phone number, area code optional. If users do not want to enter the optional characters, they can either enter spaces or place the mouse pointer directly at the position in the mask represented by the first 0.

$999,999.00

A currency value in the range of 0 to 999999. The currency, thousandth, and decimal characters will be replaced at run time with their culture-specific equivalents.

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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