Enumerable.Max<TSource> Method (IEnumerable<TSource>)

Type Parameters

• TSource
  The type of the elements of source.

Parameters

• source
  Type: System.Collections.Generic.IEnumerable<TSource>
  A sequence of values to determine the maximum value of.

Return Value

Type: TSource
The maximum value in the sequence.

   ' This class implements IComparable 
   ' and has a custom 'CompareTo' implementation.
   Class Pet
      Implements IComparable(Of Pet)

      Public Name As String
      Public Age As Integer

      ''' <summary>
      ''' Compares Pet objects by the sum of their age and name length.
      ''' </summary>
      ''' <param name="other">The Pet to compare this Pet to.</param>
      ''' <returns>-1 if this Pet's sum is 'less' than the other Pet,
      ''' 0 if they are equal,
      ''' or 1 if this Pet's sum is 'greater' than the other Pet.</returns>
      Function CompareTo(ByVal other As Pet) As Integer _
          Implements IComparable(Of Pet).CompareTo

         If (other.Age + other.Name.Length > Me.Age + Me.Name.Length) Then
            Return -1
         ElseIf (other.Age + other.Name.Length = Me.Age + Me.Name.Length) Then
            Return 0
         Else
            Return 1
         End If
      End Function
   End Class

   Sub MaxEx3()
      ' Create an array of Pet objects.
      Dim pets() As Pet = {New Pet With {.Name = "Barley", .Age = 8}, _
                           New Pet With {.Name = "Boots", .Age = 4}, _
                           New Pet With {.Name = "Whiskers", .Age = 1}}

      ' Find the "maximum" pet according to the 
      ' custom CompareTo() implementation.
      Dim max As Pet = pets.Max()

      ' Display the result.
      outputBlock.Text &= "The 'maximum' animal is " & max.Name & vbCrLf
   End Sub

   ' This code produces the following output:
   '
   ' The 'maximum' animal is Barley

      /// <summary>
      /// This class implements IComparable to be able to 
      /// compare one Pet to another Pet.
      /// </summary>
      class Pet : IComparable<Pet>
      {
         public string Name { get; set; }
         public int Age { get; set; }

         /// <summary>
         /// Compares this Pet to another Pet by 
         /// summing each Pet's age and name length.
         /// </summary>
         /// <param name="other">The Pet to compare this Pet to.</param>
         /// <returns>-1 if this Pet is 'less' than the other Pet, 
         /// 0 if they are equal,
         /// or 1 if this Pet is 'greater' than the other Pet.</returns>
         int IComparable<Pet>.CompareTo(Pet other)
         {
            int sumOther = other.Age + other.Name.Length;
            int sumThis = this.Age + this.Name.Length;

            if (sumOther > sumThis)
               return -1;
            else if (sumOther == sumThis)
               return 0;
            else
               return 1;
         }
      }

      public static void MaxEx3()
      {
         Pet[] pets = { new Pet { Name="Barley", Age=8 },
                            new Pet { Name="Boots", Age=4 },
                            new Pet { Name="Whiskers", Age=1 } };

         Pet max = pets.Max();

         outputBlock.Text += String.Format(
             "The 'maximum' animal is {0}.",
             max.Name) + "\n";
      }

      /*
       This code produces the following output:

       The 'maximum' animal is Barley.
      */