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NameValueCollection Class

Represents a collection of associated String keys and String values that can be accessed either with the key or with the index.

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

public class NameValueCollection extends NameObjectCollectionBase

This collection is based on the NameObjectCollectionBase class. However, unlike the NameObjectCollectionBase, this class stores multiple string values under a single key.

This class can be used for headers, query strings and form data.

Each element is a key/value pair.

The capacity of a NameValueCollection is the number of elements the NameValueCollection can hold. As elements are added to a NameValueCollection, the capacity is automatically increased as required through reallocation.

The hash code provider dispenses hash codes for keys in the NameValueCollection. The default hash code provider is the CaseInsensitiveHashCodeProvider.

The comparer determines whether two keys are equal. The default comparer is the CaseInsensitiveComparer.

In .NET Framework version 1.0, this class uses culture-sensitive string comparisons. However, in .NET Framework version 1.1 and later, this class uses CultureInfo.InvariantCulture when comparing strings. For more information about how culture affects comparisons and sorting, see Comparing and Sorting Data for a Specific Culture Comparing and Sorting Data for a Specific Cultureand Performing Culture-Insensitive String Operations.

a null reference (Nothing in Visual Basic) is allowed as a key or as a value.

Caution noteCaution:

The Get method does not distinguish between a null reference (Nothing in Visual Basic) which is returned because the specified key is not found and a null reference (Nothing in Visual Basic) which is returned because the value associated with the key is a null reference (Nothing in Visual Basic).

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No code example is currently available or this language may not be supported.

Public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

This implementation does not provide a synchronized (thread safe) wrapper for a NameValueCollection, but derived classes can create their own synchronized versions of the NameValueCollection using the SyncRoot property of the NameObjectCollectionBase class.

Enumerating through a collection is intrinsically not a thread safe procedure. Even when a collection is synchronized, other threads can still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0