IDictionary<TKey, TValue>.TryGetValue Method
Gets the value associated with the specified key.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- key
- Type: TKey
The key whose value to get.
- value
- Type: TValue%
When this method returns, the value associated with the specified key, if the key is found; otherwise, the default value for the type of the value parameter. This parameter is passed uninitialized.
Return Value
Type: System.Booleantrue if the object that implements IDictionary<TKey, TValue> contains an element with the specified key; otherwise, false.
| Exception | Condition |
|---|---|
| ArgumentNullException | key is null. |
This method combines the functionality of the ContainsKey method and the Item property.
If the key is not found, then the value parameter gets the appropriate default value for the value type V; for example, zero (0) for integer types, false for Boolean types, and null for reference types.
The example shows how to use the TryGetValue method to retrieve values. If a program frequently tries key values that are not in a dictionary, the TryGetValue method can be more efficient than using the Item property (the indexer in C#), which throws exceptions when attempting to retrieve nonexistent keys.
This code is part of a larger example that can be compiled and executed. See System.Collections.Generic.IDictionary<TKey, TValue>.
// 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."); } ... // The indexer throws an exception if the requested key is // not in the dictionary. try { Console.WriteLine("For key = \"tif\", value = {0}.", openWith["tif"]); } catch (KeyNotFoundException) { Console.WriteLine("Key = \"tif\" is not found."); }
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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.