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List<T>.Item Property

Gets or sets the element at the specified index.

Namespace:  System.Collections.Generic
Assembly:  mscorlib (in mscorlib.dll)

public T this[
	int index
] { get; set; }

Parameters

index
Type: System.Int32
The zero-based index of the element to get or set.

Property Value

Type: T
The element at the specified index.

Implements

IList<T>.Item[Int32]

ExceptionCondition
ArgumentOutOfRangeException

index is less than 0.

-or-

index is equal to or greater than Count.

List<T> accepts null as a valid value for reference types and allows duplicate elements.

This property provides the ability to access a specific element in the collection by using the following syntax: myCollection[index].

Retrieving the value of this property is an O(1) operation; setting the property is also an O(1) operation.

The following code example demonstrates the Item property (the indexer in C#) and various other properties and methods of the List<T> generic class. After the list has been created and populated using the Add method, an element is retrieved and displayed using the Item property.

NoteNote:

Visual Basic, C#, and C++ all have syntax for accessing the Item property without using its name. Instead, the variable containing the List<T> is used as if it were an array.

The C# language uses the this keyword to define the indexers instead of implementing the Item property. Visual Basic implements Item as a default property, which provides the same indexing functionality.

For a code example that uses the Item property to set the value of a list element, see AsReadOnly.


using System;
using System.Collections.Generic;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      List<string> dinosaurs = new List<string>();

      outputBlock.Text += String.Format("\nCapacity: {0}", dinosaurs.Capacity) + "\n";

      dinosaurs.Add("Tyrannosaurus");
      dinosaurs.Add("Amargasaurus");
      dinosaurs.Add("Mamenchisaurus");
      dinosaurs.Add("Deinonychus");
      dinosaurs.Add("Compsognathus");

      outputBlock.Text += "\n";
      foreach (string dinosaur in dinosaurs)
      {
         outputBlock.Text += dinosaur + "\n";
      }

      outputBlock.Text += String.Format("\nCapacity: {0}", dinosaurs.Capacity) + "\n";
      outputBlock.Text += String.Format("Count: {0}", dinosaurs.Count) + "\n";

      outputBlock.Text += String.Format("\nContains(\"Deinonychus\"): {0}",
          dinosaurs.Contains("Deinonychus")) + "\n";

      outputBlock.Text += String.Format("\nInsert(2, \"Compsognathus\")") + "\n";
      dinosaurs.Insert(2, "Compsognathus");

      outputBlock.Text += "\n";
      foreach (string dinosaur in dinosaurs)
      {
         outputBlock.Text += dinosaur + "\n";
      }

      outputBlock.Text += String.Format("\ndinosaurs[3]: {0}", dinosaurs[3]) + "\n";

      outputBlock.Text += "\nRemove(\"Compsognathus\")" + "\n";
      dinosaurs.Remove("Compsognathus");

      outputBlock.Text += "\n";
      foreach (string dinosaur in dinosaurs)
      {
         outputBlock.Text += dinosaur + "\n";
      }

      dinosaurs.TrimExcess();
      outputBlock.Text += "\nTrimExcess()" + "\n";
      outputBlock.Text += String.Format("Capacity: {0}", dinosaurs.Capacity) + "\n";
      outputBlock.Text += String.Format("Count: {0}", dinosaurs.Count) + "\n";

      dinosaurs.Clear();
      outputBlock.Text += "\nClear()" + "\n";
      outputBlock.Text += String.Format("Capacity: {0}", dinosaurs.Capacity) + "\n";
      outputBlock.Text += String.Format("Count: {0}", dinosaurs.Count) + "\n";
   }
}

/* This code example produces the following output:

Capacity: 0

Tyrannosaurus
Amargasaurus
Mamenchisaurus
Deinonychus
Compsognathus

Capacity: 8
Count: 5

Contains("Deinonychus"): True

Insert(2, "Compsognathus")

Tyrannosaurus
Amargasaurus
Compsognathus
Mamenchisaurus
Deinonychus
Compsognathus

dinosaurs[3]: Mamenchisaurus

Remove("Compsognathus")

Tyrannosaurus
Amargasaurus
Mamenchisaurus
Deinonychus
Compsognathus

TrimExcess()
Capacity: 5
Count: 5

Clear()
Capacity: 5
Count: 0
 */


Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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