SortedList<TKey, TValue>::TryGetValue Method (TKey, TValue%)

.NET Framework (current version)

Gets the value associated with the specified key.

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

Syntax

public:
virtual bool TryGetValue(
	TKey key,
	[OutAttribute] TValue% value
) sealed

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::Boolean

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

Implements

IDictionary<TKey, TValue>::TryGetValue(TKey, TValue%) IReadOnlyDictionary<TKey, TValue>::TryGetValue(TKey, TValue%)

Exceptions

Exception	Condition
ArgumentNullException	key is null.

Remarks

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, zero (0) for integer types, false for Boolean types, and null for reference types.

This method performs a binary search; therefore, this method is an O(log n) operation, where n is Count.

Examples

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 sorted list. 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 SortedList<TKey, TValue> class.

C++

// 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", value))
{
    Console::WriteLine("For key = \"tif\", value = {0}.", value);
}
else
{
    Console::WriteLine("Key = \"tif\" is not found.");
}

C++

// 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.");
}

Version Information

Universal Windows Platform
Available since 10
.NET Framework
Available since 2.0