SortedDictionary<TKey, TValue>.TryGetValue Method (TKey, TValue)

 
System_CAPS_noteNote

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Gets the value associated with the specified key.

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

public bool TryGetValue(
	TKey key,
	out TValue value
)

Parameters

key
Type: TKey

The key of the 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.

Return Value

Type: System.Boolean

true if the SortedDictionary<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 TValue; for example, 0 (zero) for integer types, false for Boolean types, and null for reference types.

This method is an O(log n) operation.

The example shows how to use the TryGetValue method as a more efficient way to retrieve values in a program that frequently tries keys that are not in the dictionary. For contrast, the example also shows how the Item property (the indexer in C#) throws exceptions when attempting to retrieve nonexistent keys.

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

// 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.");
}

Universal Windows Platform
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
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