List<T> Constructor (IEnumerable<T>)
Microsoft Silverlight will reach end of support after October 2021. Learn more.
Initializes a new instance of the List<T> 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)
Syntax
'Declaration
Public Sub New ( _
collection As IEnumerable(Of T) _
)
public List(
IEnumerable<T> collection
)
Parameters
- collection
Type: System.Collections.Generic.IEnumerable<T>
The collection whose elements are copied to the new list.
Exceptions
| Exception | Condition |
|---|---|
| ArgumentNullException | collection is nulla null reference (Nothing in Visual Basic). |
Remarks
The capacity of a List<T> is the number of elements that the List<T> can hold. As elements are added to a List<T>, 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<T>.
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<T>.
The elements are copied onto the List<T> 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.
Examples
The following code example demonstrates the List<T> constructor and various methods of the List<T> 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.Collections.Generic
Public Class Example
Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
Dim input() As String = {"Brachiosaurus", _
"Amargasaurus", _
"Mamenchisaurus"}
Dim dinosaurs As New List(Of String)(input)
outputBlock.Text += String.Format(vbLf & "Capacity: {0}", dinosaurs.Capacity) & vbCrLf
outputBlock.Text &= vbCrLf
For Each dinosaur As String In dinosaurs
outputBlock.Text &= dinosaur & vbCrLf
Next
outputBlock.Text &= vbLf & "AddRange(dinosaurs)" & vbCrLf
dinosaurs.AddRange(dinosaurs)
outputBlock.Text &= vbCrLf
For Each dinosaur As String In dinosaurs
outputBlock.Text &= dinosaur & vbCrLf
Next
outputBlock.Text += String.Format(vbLf & "RemoveRange(2, 2)") & vbCrLf
dinosaurs.RemoveRange(2, 2)
outputBlock.Text &= vbCrLf
For Each dinosaur As String In dinosaurs
outputBlock.Text &= dinosaur & vbCrLf
Next
input = New String() {"Tyrannosaurus", _
"Deinonychus", _
"Velociraptor"}
outputBlock.Text += String.Format(vbLf & "InsertRange(3, input)") & vbCrLf
dinosaurs.InsertRange(3, input)
outputBlock.Text &= vbCrLf
For Each dinosaur As String In dinosaurs
outputBlock.Text &= dinosaur & vbCrLf
Next
outputBlock.Text += String.Format(vbLf & "output = dinosaurs.GetRange(2, 3).ToArray") & vbCrLf
Dim output() As String = dinosaurs.GetRange(2, 3).ToArray()
outputBlock.Text &= vbCrLf
For Each dinosaur As String In output
outputBlock.Text &= dinosaur & vbCrLf
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
using System;
using System.Collections.Generic;
public class Example
{
public static void Demo(System.Windows.Controls.TextBlock outputBlock)
{
string[] input = { "Brachiosaurus",
"Amargasaurus",
"Mamenchisaurus" };
List<string> dinosaurs = new List<string>(input);
outputBlock.Text += String.Format("\nCapacity: {0}", dinosaurs.Capacity) + "\n";
outputBlock.Text += "\n";
foreach (string dinosaur in dinosaurs)
{
outputBlock.Text += dinosaur + "\n";
}
outputBlock.Text += "\nAddRange(dinosaurs)" + "\n";
dinosaurs.AddRange(dinosaurs);
outputBlock.Text += "\n";
foreach (string dinosaur in dinosaurs)
{
outputBlock.Text += dinosaur + "\n";
}
outputBlock.Text += String.Format("\nRemoveRange(2, 2)") + "\n";
dinosaurs.RemoveRange(2, 2);
outputBlock.Text += "\n";
foreach (string dinosaur in dinosaurs)
{
outputBlock.Text += dinosaur + "\n";
}
input = new string[] { "Tyrannosaurus",
"Deinonychus",
"Velociraptor"};
outputBlock.Text += String.Format("\nInsertRange(3, input)") + "\n";
dinosaurs.InsertRange(3, input);
outputBlock.Text += "\n";
foreach (string dinosaur in dinosaurs)
{
outputBlock.Text += dinosaur + "\n";
}
outputBlock.Text += String.Format("\noutput = dinosaurs.GetRange(2, 3).ToArray()") + "\n";
string[] output = dinosaurs.GetRange(2, 3).ToArray();
outputBlock.Text += "\n";
foreach (string dinosaur in output)
{
outputBlock.Text += dinosaur + "\n";
}
}
}
/* 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
*/
Version Information
Silverlight
Supported in: 5, 4, 3
Silverlight for Windows Phone
Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0
XNA Framework
Supported in: Xbox 360, Windows Phone OS 7.0
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.
See Also