List(Of T).GetRange Method
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Creates a shallow copy of a range of elements in the source List(Of T).
Assembly: mscorlib (in mscorlib.dll)
'Declaration Public Function GetRange ( _ index As Integer, _ count As Integer _ ) As List(Of T)
Parameters
- index
- Type: System.Int32
The zero-based List(Of T) index at which the range starts.
- count
- Type: System.Int32
The number of elements in the range.
Return Value
Type: System.Collections.Generic.List(Of T)A shallow copy of a range of elements in the source List(Of T).
| Exception | Condition |
|---|---|
| ArgumentOutOfRangeException | index is less than 0. -or- count is less than 0. |
| ArgumentException | index and count do not denote a valid range of elements in the List(Of T). |
A shallow copy of a collection of reference types, or a subset of that collection, contains only the references to the elements of the collection. The objects themselves are not copied. The references in the new list point to the same objects as the references in the original list.
A shallow copy of a collection of value types, or a subset of that collection, contains the elements of the collection. However, if the elements of the collection contain references to other objects, those objects are not copied. The references in the elements of the new collection point to the same objects as the references in the elements of the original collection.
In contrast, a deep copy of a collection copies the elements and everything directly or indirectly referenced by the elements.
This method is an O(n) operation, where n is count.
The following code example demonstrates the GetRange method and other methods of the List(Of T) class that act on ranges. At the end of the code example, the GetRange method is used to get three items from the list, beginning with index location 2. The ToArray method is called on the resulting List(Of T), creating an array of three elements. The elements of the array are displayed.
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