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Tuple<T1>.IStructuralComparable.CompareTo Method

Compares the current Tuple<T1> object to a specified object by using a specified comparer, 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 IStructuralComparable.CompareTo(
	Object other,
	IComparer comparer
)

Parameters

other
Type: System.Object
An object to compare with the current instance.
comparer
Type: System.Collections.IComparer
An object that provides custom rules for comparison.

Return Value

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

Value

Description

A negative integer

This instance precedes other.

Zero

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

A positive integer

This instance follows other.

Implements

IStructuralComparable.CompareTo(Object, IComparer)
ExceptionCondition
ArgumentException

other is not a Tuple<T1> object.

Although this method can be called directly, it is most commonly called by collection sorting methods that include IComparer parameters to order the members of a collection. For example, it is called by the Array.Sort(Array, IComparer) method.

Caution noteCaution:

The IStructuralComparable.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 IStructuralEquatable.Equals method.

The following example defines a generic class named DescendingComparer that implements the IComparer<T> interface. DescendingComparer sorts objects in descending rather than ascending order by reversing the value returned by the default comparer for a particular type. An instance of the generic DescendingComparer class is then passed to the Array.Sort(Array, IComparer) method to sort an array of Tuple<T1> objects in descending order. Note that the example does not directly call the IStructuralComparable.CompareTo method. This method is called implicitly by the Array.Sort(Array, IComparer) method for each element in the array.


using System;
using System.Collections.Generic;

public class DescendingComparer<T> : IComparer<T>
{
   public int Compare(T x, T y)
   {
      return -1 * Comparer<T>.Default.Compare(x, y);
   }
}

class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      Tuple<Double>[] values = { Tuple.Create(13.54),
                                  Tuple.Create(Double.NaN),
                                  Tuple.Create(-189.42993),
                                  Tuple.Create(Double.PositiveInfinity),
                                  Tuple.Create(Double.Epsilon),
                                  Tuple.Create(1.934E-17),
                                  Tuple.Create(Double.NegativeInfinity),
                                  Tuple.Create(-0.000000000003588),
                                  null };
      outputBlock.Text += "The values in unsorted order:" + "\n";
      foreach (var value in values)
         if (value != null)
            outputBlock.Text += String.Format("   {0}", value.Item1) + "\n";
         else
            outputBlock.Text += "   <null>" + "\n";
      outputBlock.Text += "\n";

      Array.Sort(values, new DescendingComparer<Tuple<Double>>());

      outputBlock.Text += "The values sorted in descending order:" + "\n";
      foreach (var value in values)
         if (value != null)
            outputBlock.Text += String.Format("   {0}", value.Item1) + "\n";
         else
            outputBlock.Text += "   <null>" + "\n";
   }
}
// The example displays the following output:
//      The values in unsorted order:
//         13.54
//         NaN
//         -189.42993
//         Infinity
//         4.94065645841247E-324
//         1.934E-17
//         -Infinity
//         -3.588E-12
//         <null>
//
//      The values sorted in descending order:
//         Infinity
//         13.54
//         1.934E-17
//         4.94065645841247E-324
//         -3.588E-12
//         -189.42993
//         -Infinity
//         NaN
//         <null>


Silverlight

Supported in: 5, 4

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

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