Dictionary<TKey, TValue> Constructor (Int32, IEqualityComparer<TKey>^)
Initializes a new instance of the Dictionary<TKey, TValue> class that is empty, has the specified initial capacity, and uses the specified IEqualityComparer<T>.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- capacity
-
Type:
System::Int32
The initial number of elements that the Dictionary<TKey, TValue> can contain.
- 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.
| Exception | Condition |
|---|---|
| ArgumentOutOfRangeException | capacity is less than 0. |
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.
The capacity of a Dictionary<TKey, TValue> is the number of elements that can be added to the Dictionary<TKey, TValue> before resizing is necessary. As elements are added to a Dictionary<TKey, TValue>, the capacity is automatically increased as required by reallocating the internal array.
If the size of the collection can be estimated, specifying the initial capacity eliminates the need to perform a number of resizing operations while adding elements to the Dictionary<TKey, TValue>.
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.
This constructor is an O(1) operation.
The following code example creates a Dictionary<TKey, TValue> with an initial capacity of 5 and 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