ArraySegment(T) Structure (System)

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Microsoft Visual Studio 2008/.NET Framework 3.5

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.NET Framework Class Library

ArraySegment<(Of <(T>)>) Structure

Updated: November 2007

Delimits a section of a one-dimensional array.

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

Syntax

Visual Basic (Declaration)

<SerializableAttribute> _
Public Structure ArraySegment(Of T)

Visual Basic (Usage)

Dim instance As ArraySegment(Of T)

[SerializableAttribute]
public struct ArraySegment<T>

Visual C++

[SerializableAttribute]
generic<typename T>
public value class ArraySegment

J# supports the use of generic APIs, but not the declaration of new ones.

JScript

JScript does not support generic types or methods.

Type Parameters

T: The type of the elements in the array segment.

Remarks

ArraySegment<(Of <(T>)>) is a wrapper around an array that delimits a range of elements in that array. Multiple ArraySegment<(Of <(T>)>) instances can refer to the same original array and can overlap.

The Array property returns the entire original array, not a copy of the array; therefore, changes made to the array returned by the Array property are made to the original array.

The original array must be one-dimensional and must have zero-based indexing.

Examples

The following code example passes an ArraySegment<(Of <(T>)>) structure to a method.

Visual Basic

Imports System

Public Class SamplesArray

    Public Shared Sub Main()

        ' Create and initialize a new string array.
        Dim myArr As String() =  {"The", "quick", "brown", "fox", "jumps", "over", "the", "lazy", "dog"}

        ' Display the initial contents of the array.
        Console.WriteLine("The original array initially contains:")
        PrintIndexAndValues(myArr)

        ' Define an array segment that contains the entire array.
        Dim myArrSegAll As New ArraySegment(Of String)(myArr)

        ' Display the contents of the ArraySegment.
        Console.WriteLine("The first array segment (with all the array's elements) contains:")
        PrintIndexAndValues(myArrSegAll)

        ' Define an array segment that contains the middle five values of the array.
        Dim myArrSegMid As New ArraySegment(Of String)(myArr, 2, 5)

        ' Display the contents of the ArraySegment.
        Console.WriteLine("The second array segment (with the middle five elements) contains:")
        PrintIndexAndValues(myArrSegMid)

        ' Modify the fourth element of the first array segment myArrSegAll.
        myArrSegAll.Array(3) = "LION"

        ' Display the contents of the second array segment myArrSegMid.
        ' Note that the value of its second element also changed.
        Console.WriteLine("After the first array segment is modified, the second array segment now contains:")
        PrintIndexAndValues(myArrSegMid)

    End Sub 'Main

    Public Shared Sub PrintIndexAndValues(arrSeg As ArraySegment(Of String))
        Dim i As Integer
        For i = arrSeg.Offset To (arrSeg.Offset + arrSeg.Count - 1)
            Console.WriteLine("   [{0}] : {1}", i, arrSeg.Array(i))
        Next i
        Console.WriteLine()
    End Sub 'PrintIndexAndValues 

    Public Shared Sub PrintIndexAndValues(myArr as String())
        Dim i As Integer
        For i = 0 To (myArr.Length - 1)
            Console.WriteLine("   [{0}] : {1}", i, myArr(i))
        Next i
        Console.WriteLine()
    End Sub 'PrintIndexAndValues 

End Class 'SamplesArray


'This code produces the following output.
'
'The original array initially contains:
'   [0] : The
'   [1] : quick
'   [2] : brown
'   [3] : fox
'   [4] : jumps
'   [5] : over
'   [6] : the
'   [7] : lazy
'   [8] : dog
'
'The first array segment (with all the array's elements) contains:
'   [0] : The
'   [1] : quick
'   [2] : brown
'   [3] : fox
'   [4] : jumps
'   [5] : over
'   [6] : the
'   [7] : lazy
'   [8] : dog
'
'The second array segment (with the middle five elements) contains:
'   [2] : brown
'   [3] : fox
'   [4] : jumps
'   [5] : over
'   [6] : the
'
'After the first array segment is modified, the second array segment now contains:
'   [2] : brown
'   [3] : LION
'   [4] : jumps
'   [5] : over
'   [6] : the

using System;

public class SamplesArray  {

   public static void Main()  {

      // Create and initialize a new string array.
      String[] myArr = { "The", "quick", "brown", "fox", "jumps", "over", "the", "lazy", "dog" };

      // Display the initial contents of the array.
      Console.WriteLine( "The original array initially contains:" );
      PrintIndexAndValues( myArr );

      // Define an array segment that contains the entire array.
      ArraySegment<String> myArrSegAll = new ArraySegment<String>( myArr );

      // Display the contents of the ArraySegment.
      Console.WriteLine( "The first array segment (with all the array's elements) contains:" );
      PrintIndexAndValues( myArrSegAll );

      // Define an array segment that contains the middle five values of the array.
      ArraySegment<String> myArrSegMid = new ArraySegment<String>( myArr, 2, 5 );

      // Display the contents of the ArraySegment.
      Console.WriteLine( "The second array segment (with the middle five elements) contains:" );
      PrintIndexAndValues( myArrSegMid );

      // Modify the fourth element of the first array segment myArrSegAll.
      myArrSegAll.Array[3] = "LION";

      // Display the contents of the second array segment myArrSegMid.
      // Note that the value of its second element also changed.
      Console.WriteLine( "After the first array segment is modified, the second array segment now contains:" );
      PrintIndexAndValues( myArrSegMid );

   }

   public static void PrintIndexAndValues( ArraySegment<String> arrSeg )  {
      for ( int i = arrSeg.Offset; i < (arrSeg.Offset + arrSeg.Count); i++ )  {
         Console.WriteLine( "   [{0}] : {1}", i, arrSeg.Array[i] );
      }
      Console.WriteLine();
   }

   public static void PrintIndexAndValues( String[] myArr )  {
      for ( int i = 0; i < myArr.Length; i++ )  {
         Console.WriteLine( "   [{0}] : {1}", i, myArr[i] );
      }
      Console.WriteLine();
   }

}


/* 
This code produces the following output.

The original array initially contains:
   [0] : The
   [1] : quick
   [2] : brown
   [3] : fox
   [4] : jumps
   [5] : over
   [6] : the
   [7] : lazy
   [8] : dog

The first array segment (with all the array's elements) contains:
   [0] : The
   [1] : quick
   [2] : brown
   [3] : fox
   [4] : jumps
   [5] : over
   [6] : the
   [7] : lazy
   [8] : dog

The second array segment (with the middle five elements) contains:
   [2] : brown
   [3] : fox
   [4] : jumps
   [5] : over
   [6] : the

After the first array segment is modified, the second array segment now contains:
   [2] : brown
   [3] : LION
   [4] : jumps
   [5] : over
   [6] : the

*/

Visual C++

using namespace System;


namespace Sample
{
    public ref class SampleArray  
    {
    public:
        static void Work()  
        {

            // Create and initialize a new string array.
            array <String^>^ words = {"The", "quick", "brown",
                "fox", "jumps", "over", "the", "lazy", "dog"};

            // Display the initial contents of the array.
            Console::WriteLine("The first array segment"
                " (with all the array's elements) contains:");
            PrintIndexAndValues(words);

            // Define an array segment that contains the entire array.
            ArraySegment<String^> segment(words);
            
            // Display the contents of the ArraySegment.
            Console::WriteLine("The first array segment"
                " (with all the array's elements) contains:");
            PrintIndexAndValues(segment);

            // Define an array segment that contains the middle five 
            // values of the array.
            ArraySegment<String^> middle(words, 2, 5);

            // Display the contents of the ArraySegment.
            Console::WriteLine("The second array segment"
                " (with the middle five elements) contains:");
            PrintIndexAndValues(middle);

            // Modify the fourth element of the first array 
            // segment
            segment.Array[3] = "LION";

            // Display the contents of the second array segment 
            // middle. Note that the value of its second element 
            // also changed.
            Console::WriteLine("After the first array segment"
                " is modified,the second array segment"
                " now contains:");
            PrintIndexAndValues(middle);
            Console::ReadLine();
        }

        static void PrintIndexAndValues(ArraySegment<String^>^ segment)  
        {
            for (int i = segment->Offset; 
                i < (segment->Offset + segment->Count); i++)  
            {
                Console::WriteLine("   [{0}] : {1}", i,
                    segment->Array[i]);
            }
            Console::WriteLine();
        }

        static void PrintIndexAndValues(array<String^>^ words) 
        {
            for (int i = 0; i < words->Length; i++)  
            {
                Console::WriteLine("   [{0}] : {1}", i,
                    words[i]);
            }
            Console::WriteLine();
        }
    };
}

int main()
{
    Sample::SampleArray::Work();
    return 0; 
}


    /* 
    This code produces the following output.

    The original array initially contains:
    [0] : The
    [1] : quick
    [2] : brown
    [3] : fox
    [4] : jumps
    [5] : over
    [6] : the
    [7] : lazy
    [8] : dog

    The first array segment (with all the array's elements) contains:
    [0] : The
    [1] : quick
    [2] : brown
    [3] : fox
    [4] : jumps
    [5] : over
    [6] : the
    [7] : lazy
    [8] : dog

    The second array segment (with the middle five elements) contains:
    [2] : brown
    [3] : fox
    [4] : jumps
    [5] : over
    [6] : the

    After the first array segment is modified, the second array segment now contains:
    [2] : brown
    [3] : LION
    [4] : jumps
    [5] : over
    [6] : the

    */

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Platforms

Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, 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

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.

Version Information