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ConcurrentDictionary<TKey, TValue> Constructor (Int32, IEnumerable<KeyValuePair<TKey, TValue>>, IEqualityComparer<TKey>)

Initializes a new instance of the ConcurrentDictionary<TKey, TValue> class that contains elements copied from the specified IEnumerable, and uses the specified IEqualityComparer<TKey>.

Namespace:  System.Collections.Concurrent
Assembly:  mscorlib (in mscorlib.dll)

public ConcurrentDictionary(
	int concurrencyLevel,
	IEnumerable<KeyValuePair<TKey, TValue>> collection,
	IEqualityComparer<TKey> comparer


Type: System.Int32
The estimated number of threads that will update the ConcurrentDictionary<TKey, TValue> concurrently.
Type: System.Collections.Generic.IEnumerable<KeyValuePair<TKey, TValue>>
The IEnumerable<KeyValuePair<TKey, TValue>> whose elements are copied to the new ConcurrentDictionary<TKey, TValue>.
Type: System.Collections.Generic.IEqualityComparer<TKey>
The IEqualityComparer<TKey> implementation to use when comparing keys.


collection is a null reference (Nothing in Visual Basic).

-or- comparer is a null reference (Nothing in Visual Basic).


concurrencyLevel is less than 1.


collection contains one or more duplicate keys.

.NET Framework

Supported in: 4

.NET Framework Client Profile

Supported in: 4

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.