Articolo
11/18/2011

Tuple<T1, T2>.IComparable.CompareTo Method

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Compares the current Tuple<T1, T2> object to a specified object and returns an integer that indicates whether the current object is before, after, or in the same position as the specified object in the sort order.

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

Syntax

'Declaration
Private Function CompareTo ( _
    obj As Object _
) As Integer Implements IComparable.CompareTo

int IComparable.CompareTo(
    Object obj
)

Parameters

obj
Type: System.Object
An object to compare with the current instance.

Return Value

Type: System.Int32
A signed integer that indicates the relative position of this instance and obj in the sort order, as shown in the following table.

Value	Description
A negative integer	This instance precedes obj.
Zero	This instance and obj have the same position in the sort order.
A positive integer	This instance follows obj.

Implements

IComparable.CompareTo(Object)

Exceptions

Exception	Condition
ArgumentException	obj is not a Tuple<T1, T2> object.

Remarks

This member is an explicit interface member implementation. It can be used only when the Tuple<T1, T2> instance is cast to an IComparable interface.

This method provides the IComparable.CompareTo implementation for the Tuple<T1, T2> class. Although the method can be called directly, it is most commonly called by the default overloads of collection sorting methods, such as Array.Sort(Array), to order the members of a collection.

Caution:
The Tuple<T1, T2>.IComparable.CompareTo method is intended for use in sorting operations. It should not be used when the primary purpose of a comparison is to determine whether two objects are equal. To determine whether two objects are equal, call the Equals method.

The Tuple<T1, T2>.IComparable.CompareTo method uses the Comparer<T>.Default comparer.

Examples

The following example creates an array of Tuple<T1, T2> objects that consist of a student's name and test score. It displays the component of each tuple in the array in unsorted order, sorts the array, and then calls ToString to display the value of each tuple in sorted order. The output shows that the array has been sorted by its first component. Note that the example does not directly call the IComparable.CompareTo(Object) method. This method is called implicitly by the Sort(Array) method for each element in the array.

Module Example
   Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      Dim scores() As Tuple(Of String, Nullable(Of Integer)) = _
                      { New Tuple(Of String, Nullable(Of Integer))("Jack", 78), _
                        New Tuple(Of String, Nullable(Of Integer))("Abbey", 92), _
                        New Tuple(Of String, Nullable(Of Integer))("Dave", 88), _
                        New Tuple(Of String, Nullable(Of Integer))("Sam", 91), _
                        New Tuple(Of String, Nullable(Of Integer))("Ed", Nothing), _
                        New Tuple(Of String, Nullable(Of Integer))("Penelope", 82), _
                        New Tuple(Of String, Nullable(Of Integer))("Linda", 99), _
                        New Tuple(Of String, Nullable(Of Integer))("Judith", 84) }

      outputBlock.Text &= "The values in unsorted order:" & vbCrLf
      For Each score In scores
         outputBlock.Text &= score.ToString() & vbCrLf
      Next
      outputBlock.Text &= vbCrLf

      Array.Sort(scores)

      outputBlock.Text &= "The values in sorted order:" & vbCrLf
      For Each score In scores
         outputBlock.Text &= score.ToString() & vbCrLf
      Next
   End Sub
End Module
' The example displays the following output;
'       The values in unsorted order:
'       (Jack, 78)
'       (Abbey, 92)
'       (Dave, 88)
'       (Sam, 91)
'       (Ed, )
'       (Penelope, 82)
'       (Linda, 99)
'       (Judith, 84)
'       
'       The values in sorted order:
'       (Abbey, 92)
'       (Dave, 88)
'       (Ed, )
'       (Jack, 78)
'       (Judith, 84)
'       (Linda, 99)
'       (Penelope, 82)
'       (Sam, 91)

using System;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      Tuple<string, Nullable<int>>[] scores = 
                    { new Tuple<string, Nullable<int>>("Jack", 78),
                      new Tuple<string, Nullable<int>>("Abbey", 92), 
                      new Tuple<string, Nullable<int>>("Dave", 88),
                      new Tuple<string, Nullable<int>>("Sam", 91), 
                      new Tuple<string, Nullable<int>>("Ed", null),
                      new Tuple<string, Nullable<int>>("Penelope", 82),
                      new Tuple<string, Nullable<int>>("Linda", 99),
                      new Tuple<string, Nullable<int>>("Judith", 84) };

      outputBlock.Text += "The values in unsorted order:" + "\n";
      foreach (Tuple<string, Nullable<int>> score in scores)
         outputBlock.Text += score.ToString() + "\n";

      outputBlock.Text += "\n";

      Array.Sort(scores);

      outputBlock.Text += "The values in sorted order:" + "\n";
      foreach (Tuple<string, Nullable<int>> score in scores)
         outputBlock.Text += score.ToString() + "\n";
   }
}
// The example displays the following output;
//       The values in unsorted order:
//       (Jack, 78)
//       (Abbey, 92)
//       (Dave, 88)
//       (Sam, 91)
//       (Ed, )
//       (Penelope, 82)
//       (Linda, 99)
//       (Judith, 84)
//       
//       The values in sorted order:
//       (Abbey, 92)
//       (Dave, 88)
//       (Ed, )
//       (Jack, 78)
//       (Judith, 84)
//       (Linda, 99)
//       (Penelope, 82)
//       (Sam, 91)

Version Information

Silverlight

Supported in: 5, 4

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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