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ListBox.TopIndex Property

Gets or sets the index of the first visible item in the ListBox.

[Visual Basic]
Public Property TopIndex As Integer
[C#]
public int TopIndex {get; set;}
[C++]
public: __property int get_TopIndex();
public: __property void set_TopIndex(int);
[JScript]
public function get TopIndex() : int;
public function set TopIndex(int);

Property Value

The zero-based index of the first visible item in the control.

Remarks

Initially, the item with the index position zero (0) is at the top of the visible region of the ListBox. If the contents of the ListBox have been scrolled, another item might be at the top of the control's display area. You can use this property to obtain the index within the ListBox.ObjectCollection for the ListBox of the item that is currently positioned at the top of the visible region of the control. You can also use this property to position an item in the list at the top of the visible region of the control.

Example

[Visual Basic, C#, C++] The following example demonstrates how to use the SelectedIndex property with the TopIndex property to move the currently selected item to the top of the list of items in the display area of the ListBox. The example further demonstrates how to remove items using the RemoveAt method of the System.Windows.Forms.ListBox.ObjectCollection class, and how to clear all item selection using the ClearSelected method. The code first moves the currently selected item in the ListBox to the top of the list. The code then removes all items before the currently selected item and clears all selections in the ListBox. This example assumes that a ListBox containing items is added to a form and that an item is currently selected in the ListBox.

[Visual Basic] 
Private Sub RemoveTopItems()
   ' Determine if the currently selected item in the ListBox 
   ' is the item displayed at the top in the ListBox.
   If listBox1.TopIndex <> listBox1.SelectedIndex Then
      ' Make the currently selected item the top item in the ListBox.
      listBox1.TopIndex = listBox1.SelectedIndex
   End If
   ' Remove all items before the top item in the ListBox.
   Dim x As Integer
   For x = listBox1.SelectedIndex - 1 To 0 Step -1
      listBox1.Items.RemoveAt(x)
   Next x

   ' Clear all selections in the ListBox.
   listBox1.ClearSelected()
End Sub 'RemoveTopItems

[C#] 
private void RemoveTopItems()
{
   // Determine if the currently selected item in the ListBox 
   // is the item displayed at the top in the ListBox.
   if (listBox1.TopIndex != listBox1.SelectedIndex)
      // Make the currently selected item the top item in the ListBox.
      listBox1.TopIndex = listBox1.SelectedIndex;

   // Remove all items before the top item in the ListBox.
   for (int x = (listBox1.SelectedIndex -1); x >= 0; x--)
   {
      listBox1.Items.RemoveAt(x);
   }

   // Clear all selections in the ListBox.
   listBox1.ClearSelected();
}

[C++] 
private:
   void RemoveTopItems()
   {
      // Determine if the currently selected item in the ListBox 
      // is the item displayed at the top in the ListBox.
      if (listBox1->TopIndex != listBox1->SelectedIndex)
         // Make the currently selected item the top item in the ListBox.
         listBox1->TopIndex = listBox1->SelectedIndex;

      // Remove all items before the top item in the ListBox.
      for (int x = (listBox1->SelectedIndex -1); x >= 0; x--)
      {
         listBox1->Items->RemoveAt(x);
      }

      // Clear all selections in the ListBox.
      listBox1->ClearSelected();
   }

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework

See Also

ListBox Class | ListBox Members | System.Windows.Forms Namespace

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