SortedList<TKey, TValue>.ContainsKey Method

Determines whether the SortedList<TKey, TValue> contains a specific key.

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

public bool ContainsKey(
	TKey key
)

Parameters

key
Type: TKey

The key to locate in the SortedList<TKey, TValue>.

Return Value

Type: System.Boolean
true if the SortedList<TKey, TValue> contains an element with the specified key; otherwise, false.

Implements

IDictionary<TKey, TValue>.ContainsKey(TKey)

ExceptionCondition
ArgumentNullException

key is null.

This method is an O(log n) operation, where n is Count.

The following code example shows how to use the ContainsKey method to test whether a key exists prior to calling the Add method. It also shows how to use the TryGetValue method to retrieve values, which is an efficient way to retrieve values when a program frequently tries keys that are not in the sorted list. Finally, it shows the least efficient way to test whether keys exist, by using the Item property (the indexer in C#).

This code example is part of a larger example provided for the SortedList<TKey, TValue> class.

// ContainsKey can be used to test keys before inserting  
// them. 
if (!openWith.ContainsKey("ht"))
{
    openWith.Add("ht", "hypertrm.exe");
    Console.WriteLine("Value added for key = \"ht\": {0}", 
        openWith["ht"]);
}


...


// When a program often has to try keys that turn out not to 
// be in the list, TryGetValue can be a more efficient  
// way to retrieve values. 
string value = "";
if (openWith.TryGetValue("tif", out value))
{
    Console.WriteLine("For key = \"tif\", value = {0}.", value);
}
else
{
    Console.WriteLine("Key = \"tif\" is not found.");
}


...


// The indexer throws an exception if the requested key is 
// not in the list. 
try
{
    Console.WriteLine("For key = \"tif\", value = {0}.", 
        openWith["tif"]);
}
catch (KeyNotFoundException)
{
    Console.WriteLine("Key = \"tif\" is not found.");
}

.NET Framework

Supported in: 4.5.2, 4.5.1, 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.

Was this page helpful?
(1500 characters remaining)
Thank you for your feedback
Show:
© 2014 Microsoft