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FileDialog.Filter Property

Gets or sets the current file name filter string, which determines the choices that appear in the "Save as file type" or "Files of type" box in the dialog box.

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

'Declaration
Public Property Filter As String

Property Value

Type: System.String
The file filtering options available in the dialog box.

ExceptionCondition
ArgumentException

Filter format is invalid.

For each filtering option, the filter string contains a description of the filter, followed by the vertical bar (|) and the filter pattern. The strings for different filtering options are separated by the vertical bar.

The following is an example of a filter string:

Text files (*.txt)|*.txt|All files (*.*)|*.*

You can add several filter patterns to a filter by separating the file types with semicolons, for example:

Image Files(*.BMP;*.JPG;*.GIF)|*.BMP;*.JPG;*.GIF|All files (*.*)|*.*

Use the FilterIndex property to set which filtering option is shown first to the user.

The following code example uses the OpenFileDialog implementation of FileDialog and illustrates creating, setting of properties, and showing the dialog box. The example uses the Filter and FilterIndex properties to provide a list of filters for the user. The example requires a form with a Button placed on it and the System.IO namespace added to it.

    Private Sub button1_Click(ByVal sender As Object, ByVal e As System.EventArgs)
        Dim myStream As Stream = Nothing 
        Dim openFileDialog1 As New OpenFileDialog()

        openFileDialog1.InitialDirectory = "c:\"
        openFileDialog1.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*"
        openFileDialog1.FilterIndex = 2
        openFileDialog1.RestoreDirectory = True 

        If openFileDialog1.ShowDialog() = System.Windows.Forms.DialogResult.OK Then 
            Try
                myStream = openFileDialog1.OpenFile()
                If (myStream IsNot Nothing) Then 
                    ' Insert code to read the stream here. 
                End If 
            Catch Ex As Exception
                MessageBox.Show("Cannot read file from disk. Original error: " & Ex.Message)
            Finally 
                ' Check this again, since we need to make sure we didn't throw an exception on open. 
                If (myStream IsNot Nothing) Then
                    myStream.Close()
                End If 
            End Try 
        End If 
    End Sub

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.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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