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

Type Parameters

• T
  The type of the elements of the array.

Parameters

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

• comparison
  Type: System.Comparison<T>
  The Comparison<T> to use when comparing elements.

Imports System.Collections.Generic

Public Class Example

   Private Shared Function CompareDinosByLength( _
       ByVal x As String, ByVal y As String) As Integer

      If x Is Nothing Then
         If y Is Nothing Then
            ' If x is Nothing and y is Nothing, they're
            ' equal. 
            Return 0
         Else
            ' If x is Nothing and y is not Nothing, y
            ' is greater. 
            Return -1
         End If
      Else
         ' If x is not Nothing...
         '
         If y Is Nothing Then
            ' ...and y is Nothing, x is greater.
            Return 1
         Else
            ' ...and y is not Nothing, compare the 
            ' lengths of the two strings.
            '
            Dim retval As Integer = _
                x.Length.CompareTo(y.Length)

            If retval <> 0 Then
               ' If the strings are not of equal length,
               ' the longer string is greater.
               '
               Return retval
            Else
               ' If the strings are of equal length,
               ' sort them with ordinary string comparison.
               '
               Return x.CompareTo(y)
            End If
         End If
      End If

   End Function

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

      Dim dinosaurs() As String = { _
          "Pachycephalosaurus", _
          "Amargasaurus", _
          "", _
          Nothing, _
          "Mamenchisaurus", _
          "Deinonychus"}
      Display(outputBlock, dinosaurs)

      outputBlock.Text &= vbLf & "Sort with generic Comparison(Of String) delegate:" & vbCrLf
      Array.Sort(dinosaurs, AddressOf CompareDinosByLength)
      Display(outputBlock, dinosaurs)

   End Sub

   Private Shared Sub Display(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal arr() As String)
      outputBlock.Text &= vbCrLf
      For Each s As String In arr
         If s Is Nothing Then
            outputBlock.Text &= "(Nothing)" & vbCrLf
         Else
            outputBlock.Text += String.Format("""{0}""", s) & vbCrLf
         End If
      Next
   End Sub
End Class

' This code example produces the following output:
'
'"Pachycephalosaurus"
'"Amargasaurus"
'""
'(Nothing)
'"Mamenchisaurus"
'"Deinonychus"
'
'Sort with generic Comparison(Of String) delegate:
'
'(Nothing)
'""
'"Deinonychus"
'"Amargasaurus"
'"Mamenchisaurus"
'"Pachycephalosaurus"

using System;
using System.Collections.Generic;

public class Example
{
   private static int CompareDinosByLength(string x, string y)
   {
      if (x == null)
      {
         if (y == null)
         {
            // If x is null and y is null, they're
            // equal. 
            return 0;
         }
         else
         {
            // If x is null and y is not null, y
            // is greater. 
            return -1;
         }
      }
      else
      {
         // If x is not null...
         //
         if (y == null)
         // ...and y is null, x is greater.
         {
            return 1;
         }
         else
         {
            // ...and y is not null, compare the 
            // lengths of the two strings.
            //
            int retval = x.Length.CompareTo(y.Length);

            if (retval != 0)
            {
               // If the strings are not of equal length,
               // the longer string is greater.
               //
               return retval;
            }
            else
            {
               // If the strings are of equal length,
               // sort them with ordinary string comparison.
               //
               return x.CompareTo(y);
            }
         }
      }
   }

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

      outputBlock.Text += "\nSort with generic Comparison<string> delegate:" + "\n";
      Array.Sort(dinosaurs, CompareDinosByLength);
      Display(outputBlock, dinosaurs);

   }

   private static void Display(System.Windows.Controls.TextBlock outputBlock, string[] arr)
   {
      outputBlock.Text += "\n";
      foreach (string s in arr)
      {
         if (s == null)
            outputBlock.Text += "(null)" + "\n";
         else
            outputBlock.Text += String.Format("\"{0}\"", s) + "\n";
      }
   }
}

/* This code example produces the following output:

"Pachycephalosaurus"
"Amargasaurus"
""
(null)
"Mamenchisaurus"
"Deinonychus"

Sort with generic Comparison<string> delegate:

(null)
""
"Deinonychus"
"Amargasaurus"
"Mamenchisaurus"
"Pachycephalosaurus"
 */