Tuple<T1>.IStructuralEquatable.Equals Method
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Returns a value that indicates whether the current Tuple<T1> object is equal to a specified object based on a specified comparison method.
Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
Private Function Equals ( _
other As Object, _
comparer As IEqualityComparer _
) As Boolean Implements IStructuralEquatable.Equals
bool IStructuralEquatable.Equals(
Object other,
IEqualityComparer comparer
)
Parameters
- other
Type: System.Object
The object to compare with this instance.
- comparer
Type: System.Collections.IEqualityComparer
An object that defines the method to use to evaluate whether the two objects are equal.
Return Value
Type: System.Boolean
true if the current instance is equal to the specified object; otherwise, false.
Implements
Remarks
This member is an explicit interface member implementation. It can be used only when the Tuple<T1> instance is cast to an IStructuralEquatable interface.
The IEqualityComparer.Equals implementation is called only if other is not nulla null reference (Nothing in Visual Basic), and if it can be successfully cast (in C#) or converted (in Visual Basic) to a Tuple<T1> object whose single component is of the same type as the current instance. The method is passed the Item1 component of the current instance and the Item1 component of the Tuple<T1> object represented by the other parameter.
Examples
The following example defines an IEqualityComparer implementation that considers two floating-point values to be equal if they are approximately equal to each other (that is, if one value is within .01 percent of the other).
Imports System.Collections
Public Class Tuple1Comparer : Implements IEqualityComparer
Public Overloads Function Equals(ByVal x As Object, ByVal y As Object) As Boolean _
Implements IEqualityComparer.Equals
' Check if x is a floating point type. If x is, then y is.
If TypeOf x Is Double Or TypeOf x Is Single Then
' Convert to Double values.
Dim dblX As Double = CDbl(x)
Dim dblY As Double = CDbl(y)
If Double.IsNaN(dblX) Or Double.IsInfinity(dblX) Or _
Double.IsNaN(dblY) Or Double.IsInfinity(dblY) Then
Return dblX.Equals(dblY)
Else
Return Math.Abs(dblX - dblY) <= dblY * 0.0001
End If
Else
Return x.Equals(y)
End If
End Function
Public Overloads Function GetHashCode(ByVal obj As Object) As Integer _
Implements IEqualityComparer.GetHashCode
Return obj.GetHashCode()
End Function
End Class
Module Example
Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
Dim doubleTuple1 = Tuple.Create(12.3455)
Dim doubleTuple2 = Tuple.Create(16.8912)
Dim doubleTuple3 = Tuple.Create(12.3449599)
' Compare first tuple with a Tuple(Of Double) with a different value.
TestEquality(outputBlock, doubleTuple1, doubleTuple2)
' Compare first tuple with a Tuple(Of Double) with the same value.
TestEquality(outputBlock, doubleTuple1, doubleTuple3)
End Sub
Private Sub TestEquality(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal tuple As Tuple(Of Double), ByVal obj As Object)
Try
outputBlock.Text += String.Format("{0} = {1}: {2}", tuple.ToString(), _
obj.ToString, _
DirectCast(tuple, IStructuralEquatable).Equals(obj, New Tuple1Comparer())) & vbCrLf
Catch e As ArgumentException
If obj.GetType.IsGenericType Then
If obj.GetType().Name = "Tuple`1" Then
outputBlock.Text += String.Format("Cannot compare a Tuple(Of {0}) with a Tuple(Of {1}).", _
tuple.Item1.GetType().Name, obj.Item1.GetType().Name) & vbCrLf
Else
outputBlock.Text += String.Format("Cannot compare a {0} with a {1}.", tuple.GetType().Name, _
obj.GetType().Name) & vbCrLf
End If
Else
outputBlock.Text += String.Format("Cannot compare a {0} with a {1}.", tuple.GetType().Name, _
obj.GetType().Name) & vbCrLf
End If
End Try
End Sub
End Module
' The example displays the following output:
' (12.3455) = (16.8912): False
' (12.3455) = (12.3449599): True
using System;
using System.Collections;
public class Tuple1Comparer : IEqualityComparer
{
new public bool Equals(object x, object y)
{
// Check if x is a floating point type. If x is, then y is.
if (x is double | x is float)
{
// Convert to Double values.
double dblX = (double)x;
double dblY = (double)y;
if (Double.IsNaN(dblX) | Double.IsInfinity(dblX) |
Double.IsNaN(dblY) | Double.IsInfinity(dblY))
return dblX.Equals(dblY);
else
return Math.Abs(dblX - dblY) <= dblX * .0001;
}
else
{
return x.Equals(y);
}
}
public int GetHashCode(object obj)
{
return obj.GetHashCode();
}
}
public class Example
{
public static void Demo(System.Windows.Controls.TextBlock outputBlock)
{
var doubleTuple1 = Tuple.Create(12.3455);
var doubleTuple2 = Tuple.Create(16.8912);
var doubleTuple3 = Tuple.Create(12.3449599);
// Compare first tuple with a Tuple<double> with a different value.
TestEquality(outputBlock, doubleTuple1, doubleTuple2);
//Compare first tuple with a Tuple<double> with the same value.
TestEquality(outputBlock, doubleTuple1, doubleTuple3);
}
private static void TestEquality(System.Windows.Controls.TextBlock outputBlock, Tuple<double> tuple, object obj)
{
outputBlock.Text += String.Format("{0} = {1}: {2}", tuple.ToString(),
obj.ToString(),
((IStructuralEquatable)tuple).Equals(obj, new Tuple1Comparer())) + "\n";
}
}
// The example displays the following output:
// (12.3455) = (16.8912): False
// (12.3455) = (12.3449599): True
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.