AutoCompleteMode Property

ComboBox::AutoCompleteMode Property


Gets or sets an option that controls how automatic completion works for the ComboBox.

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

property AutoCompleteMode AutoCompleteMode {
	AutoCompleteMode get();
	void set(AutoCompleteMode value);

Property Value

Type: System.Windows.Forms::AutoCompleteMode

One of the values of AutoCompleteMode. The values are Append, None, Suggest, and SuggestAppend. The default is None.

Exception Condition

The specified value is not one of the values of AutoCompleteMode.

Use the AutoCompleteCustomSource, AutoCompleteMode, and AutoCompleteSource properties to create a ComboBox that automatically completes input strings by comparing the prefix being entered to the prefixes of all strings in a maintained source. This is useful for ComboBox controls in which URLs, addresses, file names, or commands will be frequently entered. If there are duplicate entries in the maintained source, automatic completion behaves unpredictably.

If you set ComboBoxStyle to DropDownList, the list displays only if AutoCompleteMode is Suggest or SuggestAppend.

The use of the AutoCompleteCustomSource property is optional, but you must set the AutoCompleteSource property to CustomSource in order to use AutoCompleteCustomSource.

You must use the AutoCompleteMode and AutoCompleteSource properties together.

With AutoCompleteMode set to SuggestAppend and AutoCompleteSource set to ListItems, the behavior is as follows:

  • If the list of strings is empty, pressing the BACKSPACE or DELETE key does nothing.

  • If the BACKSPACE key is pressed in less than one second, the previous item is selected, or nothing is selected if the list of string is empty.

  • If the BACKSPACE key is pressed in more than one second, the first item is selected.

  • If the DELETE key is pressed, the first item is selected.


The operating system might limit the number of custom strings that it can display at once. For strings that contain a forward slash (/) or backward slash (\), automatic completion appends all characters only up to and including the slash.

.NET Framework
Available since 2.0
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