Array.Sort<T> Method (array<T[], IComparer<T>)

Type Parameters

• T
  The type of the elements of the array.

Parameters

• array
  Type: array<T[]
  The one-dimensional, zero-base Array to sort

• comparer
  Type: System.Collections.Generic.IComparer<T>
  The IComparer<T> generic interface implementation to use when comparing elements, or nulla null reference (Nothing in Visual Basic) to use the IComparable<T> generic interface implementation of each element.

Imports System.Collections.Generic

Public Class ReverseComparer
   Implements IComparer(Of String)

   Public Function Compare(ByVal x As String, _
       ByVal y As String) As Integer _
       Implements IComparer(Of String).Compare

      ' Compare y and x in reverse order.
      Return y.CompareTo(x)

   End Function
End Class

Public Class Example

   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)

      Dim dinosaurs() As String = { _
          "Pachycephalosaurus", _
          "Amargasaurus", _
          "Tyrannosaurus", _
          "Mamenchisaurus", _
          "Deinonychus", _
          "Edmontosaurus"}

      outputBlock.Text &= vbCrLf
      For Each dinosaur As String In dinosaurs
         outputBlock.Text &= dinosaur & vbCrLf
      Next

      Dim rc As New ReverseComparer()

      outputBlock.Text &= vbLf & "Sort" & vbCrLf
      Array.Sort(dinosaurs, rc)

      outputBlock.Text &= vbCrLf
      For Each dinosaur As String In dinosaurs
         outputBlock.Text &= dinosaur & vbCrLf
      Next

      outputBlock.Text &= vbLf & _
          "BinarySearch for 'Coelophysis':" & vbCrLf
      Dim index As Integer = _
          Array.BinarySearch(dinosaurs, "Coelophysis", rc)
      ShowWhere(outputBlock, dinosaurs, index)

      outputBlock.Text &= vbLf & _
          "BinarySearch for 'Tyrannosaurus':" & vbCrLf
      index = Array.BinarySearch(dinosaurs, "Tyrannosaurus", rc)
      ShowWhere(outputBlock, dinosaurs, index)

   End Sub

   Private Shared Sub ShowWhere(Of T) _
       (ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal array() As T, ByVal index As Integer)

      If index < 0 Then
         ' If the index is negative, it represents the bitwise
         ' complement of the next larger element in the array.
         '
         index = index Xor -1

         outputBlock.Text &= "Not found. Sorts between: "

         If index = 0 Then
            outputBlock.Text &= "beginning of array and "
         Else
            outputBlock.Text &= String.Format("{0} and ", array(index - 1))
         End If

         If index = array.Length Then
            outputBlock.Text &= "end of array." & vbCrLf
         Else
            outputBlock.Text &= String.Format("{0}.", array(index)) & vbCrLf
         End If
      Else
         outputBlock.Text &= String.Format("Found at index {0}.", index) & vbCrLf
      End If

   End Sub

End Class

' This code example produces the following output:
'
'Pachycephalosaurus
'Amargasaurus
'Tyrannosaurus
'Mamenchisaurus
'Deinonychus
'Edmontosaurus
'
'Sort
'
'Tyrannosaurus
'Pachycephalosaurus
'Mamenchisaurus
'Edmontosaurus
'Deinonychus
'Amargasaurus
'
'BinarySearch for 'Coelophysis':
'Not found. Sorts between: Deinonychus and Amargasaurus.
'
'BinarySearch for 'Tyrannosaurus':
'Found at index 0.

using System;
using System.Collections.Generic;

public class ReverseComparer : IComparer<string>
{
   public int Compare(string x, string y)
   {
      // Compare y and x in reverse order.
      return y.CompareTo(x);
   }
}

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      string[] dinosaurs = {"Pachycephalosaurus", 
                              "Amargasaurus", 
                              "Tyrannosaurus", 
                              "Mamenchisaurus", 
                              "Deinonychus", 
                              "Edmontosaurus"};

      outputBlock.Text += "\n";
      foreach (string dinosaur in dinosaurs)
      {
         outputBlock.Text += dinosaur + "\n";
      }

      ReverseComparer rc = new ReverseComparer();

      outputBlock.Text += "\nSort" + "\n";
      Array.Sort(dinosaurs, rc);

      outputBlock.Text += "\n";
      foreach (string dinosaur in dinosaurs)
      {
         outputBlock.Text += dinosaur + "\n";
      }

      outputBlock.Text += "\nBinarySearch for 'Coelophysis':" + "\n";
      int index = Array.BinarySearch(dinosaurs, "Coelophysis", rc);
      ShowWhere(outputBlock, dinosaurs, index);

      outputBlock.Text += "\nBinarySearch for 'Tyrannosaurus':" + "\n";
      index = Array.BinarySearch(dinosaurs, "Tyrannosaurus", rc);
      ShowWhere(outputBlock, dinosaurs, index);
   }

   private static void ShowWhere<T>(System.Windows.Controls.TextBlock outputBlock, T[] array, int index)
   {
      if (index < 0)
      {
         // If the index is negative, it represents the bitwise
         // complement of the next larger element in the array.
         //
         index = ~index;

         outputBlock.Text += "Not found. Sorts between: ";

         if (index == 0)
            outputBlock.Text += "beginning of array and ";
         else
            outputBlock.Text += String.Format("{0} and ", array[index - 1]);

         if (index == array.Length)
            outputBlock.Text += "end of array." + "\n";
         else
            outputBlock.Text += String.Format("{0}.", array[index]) + "\n";
      }
      else
      {
         outputBlock.Text += String.Format("Found at index {0}.", index) + "\n";
      }
   }
}

/* This code example produces the following output:

Pachycephalosaurus
Amargasaurus
Tyrannosaurus
Mamenchisaurus
Deinonychus
Edmontosaurus

Sort

Tyrannosaurus
Pachycephalosaurus
Mamenchisaurus
Edmontosaurus
Deinonychus
Amargasaurus

BinarySearch for 'Coelophysis':
Not found. Sorts between: Deinonychus and Amargasaurus.

BinarySearch for 'Tyrannosaurus':
Found at index 0.
 */