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Count Property

ListBox.SelectedIndexCollection.Count Property

Gets the number of items in the collection.

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

[BrowsableAttribute(false)]
public int Count { get; }

Property Value

Type: System.Int32
The number of items in the collection.

Implements

ICollection.Count

This property enables you to determine the number of selected items in the ListBox. You can then use this value when looping through the values of the collection and you need to provide a number of iterations to perform the loop. Unless the SelectionMode property of the ListBox is set to SelectionMode.MultiSimple or SelectionMode.MultiExtended, this property always returns a value of zero (0) or one (1) depending on whether you have a selected item.

The following example demonstrates how to use the FindString method to search for all instances of the search text in the items of the ListBox. The example uses the version of the FindString method that enables you to specify a starting search index from which to do a continual search of all items in the ListBox. The example also demonstrates how to determine when the FindString method begins searching from the top of the list after it reaches the bottom of the list of items to prevent a recursive search. Once items are found in the ListBox, they are selected using the SetSelected method.

private void FindAllOfMyString(string searchString)
{
   // Set the SelectionMode property of the ListBox to select multiple items.
   listBox1.SelectionMode = SelectionMode.MultiExtended;

   // Set our intial index variable to -1. 
   int x =-1;
   // If the search string is empty exit. 
   if (searchString.Length != 0)
   {
      // Loop through and find each item that matches the search string. 
      do
      {
         // Retrieve the item based on the previous index found. Starts with -1 which searches start.
         x = listBox1.FindString(searchString, x);
         // If no item is found that matches exit. 
         if (x != -1)
         {
            // Since the FindString loops infinitely, determine if we found first item again and exit. 
            if (listBox1.SelectedIndices.Count > 0)
            {
               if(x == listBox1.SelectedIndices[0])
                  return;
            }
            // Select the item in the ListBox once it is found.
            listBox1.SetSelected(x,true);
         }

      }while(x != -1);
   }
}

.NET Framework

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

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
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