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CheckedListBox.CheckedIndexCollection Class

Encapsulates the collection of indexes of checked items (including items in an indeterminate state) in a CheckedListBox.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)
public class CheckedIndexCollection : IList, 
	ICollection, IEnumerable

The checked indexes collection is a subset of the indexes into the collection of all items in the CheckedListBox control. These indexes specify items in a checked or indeterminate state.

The following table is an example of the indexed collection of items in the control (all items contained in the control).

Index

Item

Check State

0

object 1

Unchecked

1

object 2

Checked

2

object 3

Unchecked

3

object 4

Indeterminate

4

object 5

Checked

Based on the previous example, the following table shows the indexed collection of indexes of checked items.

Index

Index of Item

0

1

1

3

2

4

The CheckedListBox class has two members that allow you to access the stored indexes, the Item property and the IndexOf method.

Based on the previous example, a call to the Item property with a parameter value of 1 returns a value of 3. A call to IndexOf with a parameter of 3 returns a value of 1.

The following example enumerates the checked items in the CheckedListBox.CheckedIndexCollection to see what check state an item is in. The example demonstrates using the GetItemCheckState method to set the check state of an item. The example also demonstrates using the CheckedIndices property to get the CheckedListBox.CheckedIndexCollection, and the CheckedItems property to get the CheckedListBox.CheckedItemCollection.

The first loop uses the GetItemCheckState method to get the CheckState of each checked item, given the index of the item. The second loop also uses GetItemCheckState, but uses the ListBox.ObjectCollection.IndexOf method to retrieve the index for the item.

private void WhatIsChecked_Click(object sender, System.EventArgs e) {
    // Display in a message box all the items that are checked. 

    // First show the index and check state of all selected items. 
    foreach(int indexChecked in checkedListBox1.CheckedIndices) {
        // The indexChecked variable contains the index of the item.
        MessageBox.Show("Index#: " + indexChecked.ToString() + ", is checked. Checked state is:" +
                        checkedListBox1.GetItemCheckState(indexChecked).ToString() + ".");
    }

    // Next show the object title and check state for each item selected. 
    foreach(object itemChecked in checkedListBox1.CheckedItems) {

        // Use the IndexOf method to get the index of an item.
        MessageBox.Show("Item with title: \"" + itemChecked.ToString() + 
                        "\", is checked. Checked state is: " + 
                        checkedListBox1.GetItemCheckState(checkedListBox1.Items.IndexOf(itemChecked)).ToString() + ".");
    }

}
System.Object
  System.Windows.Forms.CheckedListBox.CheckedIndexCollection
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0
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