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.NET Framework 3.5
 Dictionary(TKey, TValue) Constructo...

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Microsoft Visual Studio 2008/.NET Framework 3.5

Other versions are also available for the following:
.NET Framework Class Library
Dictionary<(Of <(TKey, TValue>)>) Constructor (Int32)

Initializes a new instance of the Dictionary<(Of <(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)
Visual Basic (Declaration)
Public Sub New ( _
    capacity As Integer _
)
Visual Basic (Usage)
Dim capacity As Integer

Dim instance As New Dictionary(capacity)
C#
public Dictionary(
    int capacity
)
Visual C++
public:
Dictionary(
    int capacity
)
JScript
public function Dictionary(
    capacity : int
)

Parameters

capacity
Type: System..::.Int32
The initial number of elements that the Dictionary<(Of <(TKey, TValue>)>) can contain.
ExceptionCondition
ArgumentOutOfRangeException

capacity is less than 0.

Every key in a Dictionary<(Of <(TKey, TValue>)>) must be unique according to the default equality comparer.

The capacity of a Dictionary<(Of <(TKey, TValue>)>) is the number of elements that can be added to the Dictionary<(Of <(TKey, TValue>)>) before resizing is necessary. As elements are added to a Dictionary<(Of <(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<(Of <(TKey, TValue>)>).

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

Visual Basic
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

C#
using System;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        // Create a new dictionary of strings, with string keys and
        // an initial capacity of 4.
        Dictionary<string, string> openWith = 
                               new Dictionary<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();
        foreach( KeyValuePair<string, string> kvp in openWith )
        {
            Console.WriteLine("Key = {0}, Value = {1}", 
               kvp.Key, kvp.Value);
        }
    }
}

/* 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 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0

.NET Compact Framework

Supported in: 3.5, 2.0

XNA Framework

Supported in: 3.0, 2.0, 1.0
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