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List<T> Constructor (IEnumerable<T>)

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)

public List(
	IEnumerable<T> collection
)

Parameters

collection
Type: System.Collections.Generic.IEnumerable<T>
The collection whose elements are copied to the new list.

ExceptionCondition
ArgumentNullException

collection is null.

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.

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.


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
 */


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

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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