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SortedList<TKey, TValue>.Keys Property

Gets a collection containing the keys in the SortedList<TKey, TValue>.

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

public IList<TKey> Keys { get; }

Property Value

Type: System.Collections.Generic.IList<TKey>
A IList<T> containing the keys in the SortedList<TKey, TValue>.

The order of the keys in the IList<T> is the same as the order in the SortedList<TKey, TValue>.

The returned IList<T> is not a static copy; instead, the IList<T> refers back to the keys in the original SortedList<TKey, TValue>. Therefore, changes to the SortedList<TKey, TValue> continue to be reflected in the IList<T>.

The collection returned by the Keys property provides an efficient way to retrieve keys by index. It is not necessary to regenerate the list when the property is accessed, because the list is just a wrapper for the internal array of keys. The following code shows the use of the Keys property for indexed retrieval of keys from a sorted list of elements with string keys:

string k = mySortedList.Keys[3];

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

The following code example shows how to enumerate the keys in the sorted list using the Keys property, and how to enumerate the keys and values in the sorted list.

The example also shows how to use the Keys property for efficient indexed retrieval of keys.

This code is part of a larger example that can be compiled and executed. See SortedList<TKey, TValue>.

// To get the keys alone, use the Keys property.
IList<string> ilistKeys = openWith.Keys;

// The elements of the list are strongly typed with the 
// type that was specified for the SortedList keys.
foreach( string s in ilistKeys )
    Console.WriteLine("Key = {0}", s);

// The Keys property is an efficient way to retrieve
// keys by index.
Console.WriteLine("\nIndexed retrieval using the Keys " +
    "property: Keys[2] = {0}", openWith.Keys[2]);


// When you use foreach to enumerate list elements,
// the elements are retrieved as KeyValuePair objects.
foreach( KeyValuePair<string, string> kvp in openWith )
    Console.WriteLine("Key = {0}, Value = {1}", 
        kvp.Key, kvp.Value);

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, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

.NET Compact Framework

Supported in: 3.5, 2.0

XNA Framework

Supported in: 3.0, 2.0, 1.0