SortedList<TKey, TValue>.Keys Property

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

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 v = mySortedList.Values[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.
Console.WriteLine();
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.
Console.WriteLine();
foreach( KeyValuePair<string, string> kvp in openWith )
{
    Console.WriteLine("Key = {0}, Value = {1}", 
        kvp.Key, kvp.Value);
}

.NET Framework

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

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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