Export (0) Print
Expand All

List.List(Generic IEnumerable) Constructor

Initializes a new instance of the List class that contains elements copied from the specified collection and has sufficient capacity to accommodate the number of elements copied.

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

'Declaration
Public Sub New ( _
	collection As IEnumerable(Of T) _
)
'Usage
Dim collection As IEnumerable(Of T)

Dim instance As New List(Of T)(collection)
public List (
	IEnumerable<T> collection
)
public function List (
	collection : IEnumerable<T>
)
Not applicable.

Parameters

collection

The collection whose elements are copied to the new list.

Exception typeCondition

ArgumentNullException

collection is a null reference (Nothing in Visual Basic).

The capacity of a List is the number of elements that the List can hold. As elements are added to a List, 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 List.

The capacity can be decreased by calling the TrimExcess method or by setting the Capacity property explicitly. Decreasing the capacity reallocates memory and copies all the elements in the List.

The elements are copied onto the List in the same order they are read by the enumerator of the collection.

This constructor is an O(n) operation, where n is the number of elements in collection.

The following code example demonstrates the List constructor and various methods of the List class that act on ranges. An array of strings is created and passed to the constructor, populating the list with the elements of the array. The Capacity property is then displayed, to show that the initial capacity is exactly what is required to hold the input elements.

Imports System
Imports System.Collections.Generic

Public Class Example

    Public Shared Sub Main()

        Dim input() As String = { "Brachiosaurus", _
                                  "Amargasaurus", _
                                  "Mamenchisaurus" }

        Dim dinosaurs As New List(Of String)(input)

        Console.WriteLine(vbLf & "Capacity: {0}", dinosaurs.Capacity)

        Console.WriteLine()
        For Each dinosaur As String In dinosaurs
            Console.WriteLine(dinosaur)
        Next

        Console.WriteLine(vbLf & "AddRange(dinosaurs)")
        dinosaurs.AddRange(dinosaurs)

        Console.WriteLine()
        For Each dinosaur As String In dinosaurs
            Console.WriteLine(dinosaur)
        Next

        Console.WriteLine(vbLf & "RemoveRange(2, 2)")
        dinosaurs.RemoveRange(2, 2)

        Console.WriteLine()
        For Each dinosaur As String In dinosaurs
            Console.WriteLine(dinosaur)
        Next

        input = New String() { "Tyrannosaurus", _
                               "Deinonychus", _
                               "Velociraptor" }

        Console.WriteLine(vbLf & "InsertRange(3, input)")
        dinosaurs.InsertRange(3, input)

        Console.WriteLine()
        For Each dinosaur As String In dinosaurs
            Console.WriteLine(dinosaur)
        Next

        Console.WriteLine(vbLf & "output = dinosaurs.GetRange(2, 3).ToArray")
        Dim output() As String = dinosaurs.GetRange(2, 3).ToArray()
        
        Console.WriteLine()
        For Each dinosaur As String In output
            Console.WriteLine(dinosaur)
        Next

    End Sub
End Class

' This code example produces the following output:
'
'Capacity: 3
'
'Brachiosaurus
'Amargasaurus
'Mamenchisaurus
'
'AddRange(dinosaurs)
'
'Brachiosaurus
'Amargasaurus
'Mamenchisaurus
'Brachiosaurus
'Amargasaurus
'Mamenchisaurus
'
'RemoveRange(2, 2)
'
'Brachiosaurus
'Amargasaurus
'Amargasaurus
'Mamenchisaurus
'
'InsertRange(3, input)
'
'Brachiosaurus
'Amargasaurus
'Amargasaurus
'Tyrannosaurus
'Deinonychus
'Velociraptor
'Mamenchisaurus
'
'output = dinosaurs.GetRange(2, 3).ToArray
'
'Amargasaurus
'Tyrannosaurus
'Deinonychus

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

Community Additions

ADD
Show:
© 2014 Microsoft