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Tuple<T1, T2>.IComparable.CompareTo Method

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)

int IComparable.CompareTo(
	Object 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.



A negative integer

This instance precedes obj.


This instance and obj have the same position in the sort order.

A positive integer

This instance follows obj.




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

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) and SortedList.Add, to order the members of a collection.

Caution noteCaution

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 default object comparer to compare each component.

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.

using System;

public class Example
   public static void Main()
      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) };

      Console.WriteLine("The values in unsorted order:");
      foreach (Tuple<string, Nullable<int>> score in scores)



      Console.WriteLine("The values in sorted order:");
      foreach (Tuple<string, Nullable<int>> score in scores)
// 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)

.NET Framework

Supported in: 4.5, 4

.NET Framework Client Profile

Supported in: 4

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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