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Dictionary.Dictionary(Int32) Constructor

Initializes a new instance of the Dictionary 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)

'Declaration
Public Sub New ( _
	capacity As Integer _
)
'Usage
Dim capacity As Integer

Dim instance As New Dictionary(Of TKey, TValue)(capacity)
public Dictionary (
	int capacity
)
public function Dictionary (
	capacity : int
)
Not applicable.

Parameters

capacity

The initial number of elements that the Dictionary can contain.

Exception typeCondition

ArgumentOutOfRangeException

capacity is less than 0.

Every key in a Dictionary must be unique according to the default equality comparer.

The capacity of a Dictionary is the number of elements that can be added to the Dictionary before resizing is necessary. As elements are added to a Dictionary, 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.

Dictionary requires an equality implementation to determine whether keys are equal. This constructor uses the default generic equality comparer, EqualityComparer.Default. If type TKey implements the System.IEquatable generic interface, the default equality comparer uses that implementation. Alternatively, you can specify an implementation of the IEqualityComparer 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.

Imports System
Imports System.Collections.Generic

Public Class Example
    
    Public Shared Sub Main() 

        ' Create a new dictionary of strings, with string keys and
        ' an initial capacity of 4.
        Dim openWith As New Dictionary(Of String, String)(4)
        
        ' Add 4 elements to the dictionary. 
        openWith.Add("txt", "notepad.exe")
        openWith.Add("bmp", "paint.exe")
        openWith.Add("dib", "paint.exe")
        openWith.Add("rtf", "wordpad.exe")
        
        ' List the contents of the dictionary.
        Console.WriteLine()
        For Each kvp As KeyValuePair(Of String, String) In openWith
            Console.WriteLine("Key = {0}, Value = {1}", _
                kvp.Key, kvp.Value)
        Next kvp

    End Sub

End Class

' This code example produces the following output:
'
'Key = txt, Value = notepad.exe
'Key = bmp, Value = paint.exe
'Key = dib, Value = paint.exe
'Key = rtf, Value = wordpad.exe

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

.NET Compact Framework

Supported in: 2.0

XNA Framework

Supported in: 1.0

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