FileDialog::Filter Property
Gets or sets the filter string that determines what types of files are displayed from either the OpenFileDialog or SaveFileDialog.
Assembly: PresentationFramework (in PresentationFramework.dll)
| Exception | Condition |
|---|---|
| ArgumentException | The filter string is invalid. |
If Filter is either null or Empty, all files are displayed, and folders are always displayed.
You can specify a subset of file types to be displayed by setting the Filter property. Each file type can represent a specific type of file, such as the following:
Word Documents (*.doc)
Excel Worksheets (*.xls)
PowerPoint Presentations (*.ppt)
Alternatively, a file type can represent a group of related file types, such as the following:
Office Files (*.doc, *.xls, *.ppt)
All Files (*.*)
To specify a subset of the types of files that are displayed, you set the Filter property with a string value (the filter string) that specifies one or more types of files to filter by. The following shows the expected format of the filter string:
FileType1[[|FileType2]...[|FileTypeN]]
You use the following format to describe each file type:
Label|Extension1[[;Extension2]...[;ExtensionN]]
The Label part is a human-readable string value that describes the file type, such as the following:
"Word Documents"
"Excel Worksheets"
"PowerPoint Presentations"
"Office Files"
"All Files"
Each file type must be described by at least one Extension. If more than one Extension is used, each Extension must be separated by a semicolon (";"). For example:
"*.doc"
"*.xls;"
"*.ppt"
"*.doc;*.xls;*.ppt"
"*.*"
The following are complete examples of valid Filter string values:
Word Documents|*.doc
Excel Worksheets|*.xls
PowerPoint Presentations|*.ppt
Office Files|*.doc;*.xls;*.ppt
All Files|*.*
Word Documents|*.doc|Excel Worksheets|*.xls|PowerPoint Presentations|*.ppt|Office Files|*.doc;*.xls;*.ppt|All Files|*.*
Each file type that is included in the filter is added as a separate item to the Files of type: drop-down list in the OpenFileDialog or SaveFileDialog, as shown in the following figure.

The user can choose a file type from this list to filter by. By default, the first item in the list (for example, the first file type) is selected when the OpenFileDialog or SaveFileDialog is displayed. To specify that another file type to be selected, you set the FilterIndex property before showing the OpenFileDialog or SaveFileDialog (by calling ShowDialog).
The following examples demonstrate several types of filter strings that can be set by using the Filter property.
Available since 3.0