Dictionary<'TKey, 'TValue> Constructor (Int32)


Initializes a new instance of the Dictionary<'TKey, 'TValue> class that is empty, has the specified initial capacity, and uses the default equality comparer for the key type.

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

new : 
        capacity:int -> Dictionary


Type: System.Int32

The initial number of elements that the Dictionary<'TKey, 'TValue> can contain.

Exception Condition

capacity is less than 0.

Every key in a Dictionary<'TKey, 'TValue> must be unique according to the default equality 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. 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. Alternatively, you can specify an implementation of the IEqualityComparer<'T> generic interface by using a constructor that accepts a comparer parameter.

This constructor is an O(1) operation.

The following code example creates a dictionary with an initial capacity of 4 and populates it with 4 entries.

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

Universal Windows Platform
Available since 8
.NET Framework
Available since 2.0
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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