Array.Reverse Array.Reverse Array.Reverse Array.Reverse Method

Definition

Reverses the order of the elements in a one-dimensional Array or in a portion of the Array.

Overloads

Reverse(Array, Int32, Int32) Reverse(Array, Int32, Int32) Reverse(Array, Int32, Int32)

Reverses the sequence of the elements in a range of elements in the one-dimensional Array.

Reverse(Array) Reverse(Array) Reverse(Array)

Reverses the sequence of the elements in the entire one-dimensional Array.

Reverse<T>(T[]) Reverse<T>(T[]) Reverse<T>(T[]) Reverse<T>(T[])
Reverse<T>(T[], Int32, Int32) Reverse<T>(T[], Int32, Int32) Reverse<T>(T[], Int32, Int32) Reverse<T>(T[], Int32, Int32)

Reverse(Array, Int32, Int32) Reverse(Array, Int32, Int32) Reverse(Array, Int32, Int32)

Reverses the sequence of the elements in a range of elements in the one-dimensional Array.

public:
 static void Reverse(Array ^ array, int index, int length);
public static void Reverse (Array array, int index, int length);
static member Reverse : Array * int * int -> unit

Parameters

array
Array Array Array Array

The one-dimensional Array to reverse.

index
Int32 Int32 Int32 Int32

The starting index of the section to reverse.

length
Int32 Int32 Int32 Int32

The number of elements in the section to reverse.

Exceptions

index is less than the lower bound of array.

-or-

length is less than zero.

index and length do not specify a valid range in array.

Examples

The following code example shows how to reverse the sort of the values in a range of elements in an Array.

using namespace System;
void PrintIndexAndValues( Array^ myArray );
void main()
{
   // Creates and initializes a new Array instance.
   Array^ myArray = Array::CreateInstance( String::typeid, 9 );
   myArray->SetValue( "The", 0 );
   myArray->SetValue( "QUICK", 1 );
   myArray->SetValue( "BROWN", 2 );
   myArray->SetValue( "FOX", 3 );
   myArray->SetValue( "jumps", 4 );
   myArray->SetValue( "over", 5 );
   myArray->SetValue( "the", 6 );
   myArray->SetValue( "lazy", 7 );
   myArray->SetValue( "dog", 8 );

   // Displays the values of the Array.
   Console::WriteLine(  "The Array instance initially contains the following values:" );
   PrintIndexAndValues( myArray );

   // Reverses the sort of the values of the Array.
   Array::Reverse( myArray, 1, 3 );

   // Displays the values of the Array.
   Console::WriteLine(  "After reversing:" );
   PrintIndexAndValues( myArray );
}

void PrintIndexAndValues( Array^ myArray )
{
   for ( int i = myArray->GetLowerBound( 0 ); i <= myArray->GetUpperBound( 0 ); i++ )
      Console::WriteLine(  "\t[{0}]:\t{1}", i, myArray->GetValue( i ) );
}

/* 
 This code produces the following output.
 
 The Array instance initially contains the following values:
     [0]:    The
     [1]:    QUICK
     [2]:    BROWN
     [3]:    FOX
     [4]:    jumps
     [5]:    over
     [6]:    the
     [7]:    lazy
     [8]:    dog
 After reversing:
     [0]:    The
     [1]:    FOX
     [2]:    BROWN
     [3]:    QUICK
     [4]:    jumps
     [5]:    over
     [6]:    the
     [7]:    lazy
     [8]:    dog
 */
using System;
public class SamplesArray  {

   public static void Main()  {

      // Creates and initializes a new Array.
      Array myArray=Array.CreateInstance( typeof(String), 9 );
      myArray.SetValue( "The", 0 );
      myArray.SetValue( "QUICK", 1 );
      myArray.SetValue( "BROWN", 2 );
      myArray.SetValue( "FOX", 3 );
      myArray.SetValue( "jumps", 4 );
      myArray.SetValue( "over", 5 );
      myArray.SetValue( "the", 6 );
      myArray.SetValue( "lazy", 7 );
      myArray.SetValue( "dog", 8 );

      // Displays the values of the Array.
      Console.WriteLine( "The Array initially contains the following values:" );
      PrintIndexAndValues( myArray );

      // Reverses the sort of the values of the Array.
      Array.Reverse( myArray, 1, 3 );

      // Displays the values of the Array.
      Console.WriteLine( "After reversing:" );
      PrintIndexAndValues( myArray );
   }


   public static void PrintIndexAndValues( Array myArray )  {
      for ( int i = myArray.GetLowerBound(0); i <= myArray.GetUpperBound(0); i++ )
         Console.WriteLine( "\t[{0}]:\t{1}", i, myArray.GetValue( i ) );
   }
}
/* 
This code produces the following output.

The Array initially contains the following values:
    [0]:    The
    [1]:    QUICK
    [2]:    BROWN
    [3]:    FOX
    [4]:    jumps
    [5]:    over
    [6]:    the
    [7]:    lazy
    [8]:    dog
After reversing:
    [0]:    The
    [1]:    FOX
    [2]:    BROWN
    [3]:    QUICK
    [4]:    jumps
    [5]:    over
    [6]:    the
    [7]:    lazy
    [8]:    dog
*/ 
Imports System
Imports Microsoft.VisualBasic

Public Class SamplesArray    
    
    Public Shared Sub Main()
        
        ' Creates and initializes a new Array.
        Dim myArray As Array = Array.CreateInstance(GetType(String), 9)
        myArray.SetValue("The", 0)
        myArray.SetValue("QUICK", 1)
        myArray.SetValue("BROWN", 2)
        myArray.SetValue("FOX", 3)
        myArray.SetValue("jumps", 4)
        myArray.SetValue("over", 5)
        myArray.SetValue("the", 6)
        myArray.SetValue("lazy", 7)
        myArray.SetValue("dog", 8)
        
        ' Displays the values of the Array.
        Console.WriteLine("The Array initially contains the " _
           + "following values:")
        PrintIndexAndValues(myArray)
        
        ' Reverses the sort of the values of the Array.
        Array.Reverse(myArray, 1, 3)
        
        ' Displays the values of the Array.
        Console.WriteLine("After reversing:")
        PrintIndexAndValues(myArray)
    End Sub    
    
    
    Public Shared Sub PrintIndexAndValues(myArray As Array)
        Dim i As Integer
        For i = myArray.GetLowerBound(0) To myArray.GetUpperBound(0)
            Console.WriteLine(ControlChars.Tab + "[{0}]:" + ControlChars.Tab _
               + "{1}", i, myArray.GetValue(i))
        Next i
    End Sub
End Class

' This code produces the following output.
' 
' The Array initially contains the following values:
'     [0]:    The
'     [1]:    QUICK
'     [2]:    BROWN
'     [3]:    FOX
'     [4]:    jumps
'     [5]:    over
'     [6]:    the
'     [7]:    lazy
'     [8]:    dog
' After reversing:
'     [0]:    The
'     [1]:    FOX
'     [2]:    BROWN
'     [3]:    QUICK
'     [4]:    jumps
'     [5]:    over
'     [6]:    the
'     [7]:    lazy
'     [8]:    dog 

Remarks

After a call to this method, the element at myArray[i], where i is any index in the array, moves to myArray[j], where j equals (myArray.Length + myArray.GetLowerBound(0)) - (i - myArray.GetLowerBound(0)) - 1.

The Reverse method can be used to reverse a jagged array.

This method is an O(n) operation, where n is length.

Reverse(Array) Reverse(Array) Reverse(Array)

Reverses the sequence of the elements in the entire one-dimensional Array.

public:
 static void Reverse(Array ^ array);
public static void Reverse (Array array);
static member Reverse : Array -> unit

Parameters

array
Array Array Array Array

The one-dimensional Array to reverse.

Exceptions

Examples

The following code example shows how to reverse the sort of the values in an Array.

using namespace System;
void PrintIndexAndValues( Array^ myArray );
void main()
{
   // Creates and initializes a new Array instance.
   Array^ myArray = Array::CreateInstance( String::typeid, 9 );
   myArray->SetValue( "The", 0 );
   myArray->SetValue( "quick", 1 );
   myArray->SetValue( "brown", 2 );
   myArray->SetValue( "fox", 3 );
   myArray->SetValue( "jumps", 4 );
   myArray->SetValue( "over", 5 );
   myArray->SetValue( "the", 6 );
   myArray->SetValue( "lazy", 7 );
   myArray->SetValue( "dog", 8 );

   // Displays the values of the Array.
   Console::WriteLine(  "The Array instance initially contains the following values:" );
   PrintIndexAndValues( myArray );

   // Reverses the sort of the values of the Array.
   Array::Reverse( myArray );
   
   // Displays the values of the Array.
   Console::WriteLine(  "After reversing:" );
   PrintIndexAndValues( myArray );
}

void PrintIndexAndValues( Array^ myArray )
{
   for ( int i = myArray->GetLowerBound( 0 ); i <= myArray->GetUpperBound( 0 ); i++ )
      Console::WriteLine(  "\t[{0}]:\t{1}", i, myArray->GetValue( i ) );
}

/* 
 This code produces the following output.
 
 The Array instance initially contains the following values:
     [0]:    The
     [1]:    quick
     [2]:    brown
     [3]:    fox
     [4]:    jumps
     [5]:    over
     [6]:    the
     [7]:    lazy
     [8]:    dog
 After reversing:
     [0]:    dog
     [1]:    lazy
     [2]:    the
     [3]:    over
     [4]:    jumps
     [5]:    fox
     [6]:    brown
     [7]:    quick
     [8]:    The
 */
using System;
public class SamplesArray  {

   public static void Main()  {

      // Creates and initializes a new Array.
      Array myArray=Array.CreateInstance( typeof(String), 9 );
      myArray.SetValue( "The", 0 );
      myArray.SetValue( "quick", 1 );
      myArray.SetValue( "brown", 2 );
      myArray.SetValue( "fox", 3 );
      myArray.SetValue( "jumps", 4 );
      myArray.SetValue( "over", 5 );
      myArray.SetValue( "the", 6 );
      myArray.SetValue( "lazy", 7 );
      myArray.SetValue( "dog", 8 );

      // Displays the values of the Array.
      Console.WriteLine( "The Array initially contains the following values:" );
      PrintIndexAndValues( myArray );

      // Reverses the sort of the values of the Array.
      Array.Reverse( myArray );

      // Displays the values of the Array.
      Console.WriteLine( "After reversing:" );
      PrintIndexAndValues( myArray );
   }


   public static void PrintIndexAndValues( Array myArray )  {
      for ( int i = myArray.GetLowerBound(0); i <= myArray.GetUpperBound(0); i++ )
         Console.WriteLine( "\t[{0}]:\t{1}", i, myArray.GetValue( i ) );
   }
}
/* 
This code produces the following output.

The Array initially contains the following values:
    [0]:    The
    [1]:    quick
    [2]:    brown
    [3]:    fox
    [4]:    jumps
    [5]:    over
    [6]:    the
    [7]:    lazy
    [8]:    dog
After reversing:
    [0]:    dog
    [1]:    lazy
    [2]:    the
    [3]:    over
    [4]:    jumps
    [5]:    fox
    [6]:    brown
    [7]:    quick
    [8]:    The
*/ 
Imports System
Imports Microsoft.VisualBasic

Public Class SamplesArray    
    
    Public Shared Sub Main()
        
        ' Creates and initializes a new Array.
        Dim myArray As Array = Array.CreateInstance(GetType(String), 9)
        myArray.SetValue("The", 0)
        myArray.SetValue("quick", 1)
        myArray.SetValue("brown", 2)
        myArray.SetValue("fox", 3)
        myArray.SetValue("jumps", 4)
        myArray.SetValue("over", 5)
        myArray.SetValue("the", 6)
        myArray.SetValue("lazy", 7)
        myArray.SetValue("dog", 8)
        
        ' Displays the values of the Array.
        Console.WriteLine("The Array initially contains the " _
           + "following values:")
        PrintIndexAndValues(myArray)
        
        ' Reverses the sort of the values of the Array.
        Array.Reverse(myArray)
        
        ' Displays the values of the Array.
        Console.WriteLine("After reversing:")
        PrintIndexAndValues(myArray)
    End Sub 'Main
    
    
    
    Public Shared Sub PrintIndexAndValues(myArray As Array)
        Dim i As Integer
        For i = myArray.GetLowerBound(0) To myArray.GetUpperBound(0)
            Console.WriteLine(ControlChars.Tab + "[{0}]:" + ControlChars.Tab _
               + "{1}", i, myArray.GetValue(i))
        Next i
    End Sub
End Class

' This code produces the following output.
' 
' The Array initially contains the following values:
'     [0]:    The
'     [1]:    quick
'     [2]:    brown
'     [3]:    fox
'     [4]:    jumps
'     [5]:    over
'     [6]:    the
'     [7]:    lazy
'     [8]:    dog
' After reversing:
'     [0]:    dog
'     [1]:    lazy
'     [2]:    the
'     [3]:    over
'     [4]:    jumps
'     [5]:    fox
'     [6]:    brown
'     [7]:    quick
'     [8]:    The 

Remarks

After a call to this method, the element at myArray[i], where i is any index in the array, moves to myArray[j], where j equals (myArray.Length + myArray.GetLowerBound(0)) - (i - myArray.GetLowerBound(0)) - 1.

This method is an O(n) operation, where n is the Length of array.

As the following example shows, the Reverse method can be used to reverse a jagged array. It initializes a jagged array with one element for each month of the current year in the current culture's calendar. Each element contains an array with as many elements as that month has days. The example displays the contents of the array, calls the Reverse method, and then displays the contents of the reversed array.

using System;
using System.Globalization;

public class Example
{
   public static void Main()
   {
      int nMonths = DateTimeFormatInfo.CurrentInfo.Calendar.GetMonthsInYear(DateTime.Now.Year);
      int[][] months = new int[nMonths][];

      // Populate elements with number of days in month.
      for (int ctr = 0; ctr <= months.GetUpperBound(0); ctr++) {
         int daysInMonth = DateTime.DaysInMonth(DateTime.Now.Year, ctr + 1);
         months[ctr] = new int[daysInMonth] ;
         for (int ctr2 = 1; ctr2 <= daysInMonth; ctr2++)
            months[ctr][ctr2 - 1] = ctr2;

      }

      foreach (var month in months) {
         foreach (var day in month)
            Console.Write("{0} ", day);

         Console.WriteLine();
      }
      Console.WriteLine();
               
      Console.WriteLine("About to reverse array.\n");
      Array.Reverse(months);

      foreach (var month in months) {
         foreach (var day in month)
            Console.Write("{0} ", day);

         Console.WriteLine();
      }
   }
}
// The example displays output similar to the following:
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
//    
//    About to reverse array.
//    
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
//    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Imports System.Globalization

Module Example
   Public Sub Main()
      Dim nMonths As Integer = DateTimeFormatInfo.CurrentInfo.Calendar.GetMonthsInYear(Date.Now.Year)
      Dim months()() As Integer = New Integer(nMonths - 1)() {}

      ' Populate elements with number of days in month.
      For ctr As Integer = 0 To months.GetUpperBound(0)
         Dim daysInMonth As Integer = DateTime.DaysInMonth(Date.Now.Year, ctr + 1)
         months(ctr) = New Integer(daysInMonth - 1) {}
         For ctr2 As Integer = 1 To daysInMonth
            months(ctr)(ctr2 - 1) = ctr2
         Next
      Next

      For Each _month In months
         For each _day In _month
            Console.Write("{0} ", _day)
         Next   
         Console.WriteLine()
      Next
      Console.WriteLine()
               
      Console.WriteLine("About to reverse array.")
      Console.WriteLine()
      Array.Reverse(months)

      For Each _month In months
         For each _day In _month
            Console.Write("{0} ", _day)
         Next   
         Console.WriteLine()
      Next
   End Sub
End Module
' The example displays output similar to the following:
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
'    
'    About to reverse array.
'    
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29
'    1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Reverse<T>(T[]) Reverse<T>(T[]) Reverse<T>(T[]) Reverse<T>(T[])

public:
generic <typename T>
 static void Reverse(cli::array <T> ^ array);
public static void Reverse<T> (T[] array);
static member Reverse : 'T[] -> unit
Public Shared Sub Reverse(Of T) (array As T())

Type Parameters

T

Parameters

array
T[]

Reverse<T>(T[], Int32, Int32) Reverse<T>(T[], Int32, Int32) Reverse<T>(T[], Int32, Int32) Reverse<T>(T[], Int32, Int32)

public:
generic <typename T>
 static void Reverse(cli::array <T> ^ array, int index, int length);
public static void Reverse<T> (T[] array, int index, int length);
static member Reverse : 'T[] * int * int -> unit
Public Shared Sub Reverse(Of T) (array As T(), index As Integer, length As Integer)

Type Parameters

T

Parameters

array
T[]

Applies to