SortedDictionary<TKey, TValue>.ContainsKey Method (TKey)
Determines whether the SortedDictionary<TKey, TValue> contains an element with the specified key.
Assembly: System (in System.dll)
Parameters
- key
-
Type:
TKey
The key to locate in the SortedDictionary<TKey, TValue>.
Return Value
Type: System.Booleantrue if the SortedDictionary<TKey, TValue> contains an element with the specified key; otherwise, false.
| Exception | Condition |
|---|---|
| ArgumentNullException | key is null. |
This method is an O(log n) operation.
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 dictionary. 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 SortedDictionary<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 dictionary, 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."); }
Available since 8
.NET Framework
Available since 2.0
Portable Class Library
Supported in: portable .NET platforms
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1