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Hashtable Constructor (IDictionary, Single, IHashCodeProvider, IComparer)

Note: This API is now obsolete.

Initializes a new instance of the Hashtable class by copying the elements from the specified dictionary to the new Hashtable object. The new Hashtable object has an initial capacity equal to the number of elements copied, and uses the specified load factor, hash code provider, and comparer.

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

[<ObsoleteAttribute("Please use Hashtable(IDictionary, float, IEqualityComparer) instead.")>]
new : 
        d:IDictionary * 
        loadFactor:float32 * 
        hcp:IHashCodeProvider * 
        comparer:IComparer -> Hashtable

Parameters

d
Type: System.Collections.IDictionary

The IDictionary object to copy to a new Hashtable object.

loadFactor
Type: System.Single

A number in the range from 0.1 through 1.0 that is multiplied by the default value which provides the best performance. The result is the maximum ratio of elements to buckets.

hcp
Type: System.Collections.IHashCodeProvider

The IHashCodeProvider object that supplies the hash codes for all keys in the Hashtable.

-or-

a null reference (Nothing in Visual Basic) to use the default hash code provider, which is each key's implementation of Object.GetHashCode.

comparer
Type: System.Collections.IComparer

The IComparer object to use to determine whether two keys are equal.

-or-

a null reference (Nothing in Visual Basic) to use the default comparer, which is each key's implementation of Object.Equals.

ExceptionCondition
ArgumentNullException

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

ArgumentOutOfRangeException

loadFactor is less than 0.1.

-or-

loadFactor is greater than 1.0.

The initial capacity is set to the number of elements in the source dictionary. Capacity is automatically increased as required based on the load factor.

The load factor is the maximum ratio of elements to buckets. A smaller load factor means faster lookup at the cost of increased memory consumption. A load factor of 1.0 is the best balance between speed and size.

When the actual load factor reaches the specified load factor, the number of buckets is automatically increased to the smallest prime number that is larger than twice the current number of buckets.

The hash code provider dispenses hash codes for keys in the Hashtable object. The default hash code provider is the key's implementation of Object.GetHashCode.

The comparer determines whether two keys are equal. Every key in a Hashtable must be unique. The default comparer is the key's implementation of Object.Equals.

The custom hash code provider and the custom comparer enable scenarios such as doing lookups with case-insensitive strings.

The elements of the new Hashtable are sorted in the same order in which the enumerator iterates through the IDictionary object.

This constructor is an O(n) operation, where n is the number of elements in the d parameter.

The following code example creates hash tables using different Hashtable constructors and demonstrates the differences in the behavior of the hash tables, even if each one contains the same elements.

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

.NET Framework

Supported in: 1.1, 1.0
Obsolete (compiler warning) in 4.5.2
Obsolete (compiler warning) in 4.5.1
Obsolete (compiler warning) in 4.5
Obsolete (compiler warning) in 4
Obsolete (compiler warning) in 3.5
Obsolete (compiler warning) in 3.5 SP1
Obsolete (compiler warning) in 3.0
Obsolete (compiler warning) in 3.0 SP1
Obsolete (compiler warning) in 3.0 SP2
Obsolete (compiler warning) in 2.0
Obsolete (compiler warning) in 2.0 SP1
Obsolete (compiler warning) in 2.0 SP2

.NET Framework Client Profile

Obsolete (compiler warning) in 4
Obsolete (compiler warning) in 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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