Assembly: System (in System.dll)
The underlying structure for this class is a hash table.
Each element is a key/value pair.
The capacity of a is the number of elements the can hold. As elements are added to a , the capacity is automatically increased as required through reallocation.
The hash code provider dispenses hash codes for keys in the instance. 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.
The BaseGet 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).
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 , but derived classes can create their own synchronized versions of the using the SyncRoot property.
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.