Dictionary<TKey, TValue> Constructor (IEqualityComparer<TKey>^)
Initializes a new instance of the Dictionary<TKey, TValue> class that is empty, has the default initial capacity, and uses the specified IEqualityComparer<T>.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- comparer
-
Type:
System.Collections.Generic::IEqualityComparer<TKey>^
The IEqualityComparer<T> implementation to use when comparing keys, or null to use the default EqualityComparer<T> for the type of the key.
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.
Dictionary<TKey, TValue> requires an equality implementation to determine whether keys are equal. If comparer is null, 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.
Note |
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If you can estimate the size of the collection, using a constructor that specifies the initial capacity eliminates the need to perform a number of resizing operations while adding elements to the Dictionary<TKey, TValue>. |
This constructor is an O(1) operation.
The following code example creates a Dictionary<TKey, TValue> with a case-insensitive equality comparer for the current culture. The example adds four elements, some with lower-case keys and some with upper-case keys. The example then attempts to add an element with a key that differs from an existing key only by case, catches the resulting exception, and displays an error message. Finally, the example displays the elements in the dictionary.
Available since 8
.NET Framework
Available since 2.0
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
