Tuple<T1>.IStructuralComparable.CompareTo Method
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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)
Syntax
'Declaration
Private Function CompareTo ( _
other As Object, _
comparer As IComparer _
) As Integer Implements IStructuralComparable.CompareTo
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
Remarks
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.
.gif "Caution note") Caution: |
|---|
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. |
Examples
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.
Imports System.Collections.Generic
Public Class DescendingComparer(Of T) : Implements IComparer(Of T)
Public Function Compare(ByVal x As T, ByVal y As T) As Integer Implements IComparer(Of T).Compare
Return -1 * Comparer(Of T).Default.Compare(x, y)
End Function
End Class
Module Example
Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
try
Dim values() As Tuple(Of Double) = { 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), _
Nothing}
outputBlock.Text &= "The values in unsorted order:" & vbCrLf
For Each value As Tuple(Of Double) In values
If value IsNot Nothing Then
outputBlock.Text += String.Format(" {0}", value.Item1) & vbCrLf
Else
outputBlock.Text &= " <null>" & vbCrLf
End If
Next
outputBlock.Text &= vbCrLf
Array.Sort(values, New DescendingComparer(Of Tuple(Of Double)))
outputBlock.Text &= "The values sorted in descending order:" & vbCrLf
For Each value As Tuple(Of Double) In values
If value IsNot Nothing Then
outputBlock.Text += String.Format(" {0}", value.Item1) & vbCrLf
Else
outputBlock.Text &= " <null>" & vbCrLf
End If
Next
catch e As Exception
outputBlock.Text += e.GetType().Name + ": " + e.Message + vbCrLf
end try
End Sub
End Module
' 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>
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>
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.