Article
11/18/2011

Dictionary<TKey, TValue> Constructor (IDictionary<TKey, TValue>, IEqualityComparer<TKey>)

Microsoft Silverlight will reach end of support after October 2021. Learn more.

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

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

Syntax

'Declaration
Public Sub New ( _
    dictionary As IDictionary(Of TKey, TValue), _
    comparer As IEqualityComparer(Of TKey) _
)

public Dictionary(
    IDictionary<TKey, TValue> dictionary,
    IEqualityComparer<TKey> comparer
)

Parameters

dictionary
Type: System.Collections.Generic.IDictionary<TKey, TValue>
The IDictionary<TKey, TValue> whose elements are copied to the new Dictionary<TKey, TValue>.

comparer
Type: System.Collections.Generic.IEqualityComparer<TKey>
The IEqualityComparer<T> implementation to use when comparing keys, or nulla null reference (Nothing in Visual Basic) to use the default EqualityComparer<T> for the type of the key.

Exceptions

Exception	Condition
ArgumentNullException	dictionary is nulla null reference (Nothing in Visual Basic).
ArgumentException	dictionary contains one or more duplicate keys.

Remarks

Use this constructor with the case-insensitive string comparers provided by the StringComparer class to create dictionaries with case-insensitive string keys.

Every key in a Dictionary<TKey, TValue> must be unique according to the specified comparer; likewise, every key in the source dictionary must also be unique according to the specified comparer.

Note:
For example, duplicate keys can occur if comparer is one of the case-insensitive string comparers provided by the StringComparer class and dictionary does not use a case-insensitive comparer key.

The initial capacity of the new Dictionary<TKey, TValue> is large enough to contain all the elements in dictionary.

Dictionary<TKey, TValue> requires an equality implementation to determine whether keys are equal. If comparer is nulla null reference (Nothing in Visual Basic), this constructor uses the default generic equality comparer, EqualityComparer<T>.Default. If type TKey implements the System.IEquatable<T> generic interface, the default equality comparer uses that implementation.

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

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Share via