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Tuple<T1, T2, T3, T4, T5>.IStructuralEquatable.Equals Method

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Returns a value that indicates whether the current Tuple<T1, T2, T3, T4, T5> 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.

Return Value

Type: System.Boolean
true if the current instance is equal to the specified object; otherwise, false.

Implements

IStructuralEquatable.Equals(Object, IEqualityComparer)

Remarks

This member is an explicit interface member implementation. It can be used only when the Tuple<T1, T2, T3, T4, T5> 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, T2, T3, T4, T5> object whose components are of the same types as the current instance. The IStructuralEquatable.Equals(Object, IEqualityComparer) method first passes the Item1 values of the Tuple<T1, T2, T3, T4, T5> objects to be compared to the IEqualityComparer.Equals implementation. If this method call returns true, the method is called again and passed the Item2 values of the two Tuple<T1, T2, T3, T4, T5> objects. This continues until the method call returns false when it compares a specific pair of Item values, or the two Item5 values are passed to the method.

Examples

The following example defines a DoubleComparer class that implements the IEqualityComparer interface. The example instantiates two Tuple<T1, T2, T3, T4, T5> objects by using a random number generator to populate their second through fifth components, casts the first instance to an IStructuralEquatable interface, and then uses a DoubleComparer object to test the two Tuple<T1, T2, T3, T4, T5> objects for approximate equality.

Imports System.Collections

Public Class DoubleComparer(Of T1, T2, T3, T4, T5) : Implements IEqualityComparer
   Private difference As Double
   Private argument As Integer = 0

   Public Sub New(ByVal difference As Double)
      Me.difference = difference
   End Sub

   Public Overloads Function Equals(ByVal x As Object, ByVal y As Object) As Boolean _
                   Implements IEqualityComparer.Equals
      argument += 1

      ' Return true for Item1.
      If argument = 1 Then
         Return True
      Else
         Dim d1 As Double = CDbl(x)
         Dim d2 As Double = CDbl(y)
         If d1 - d2 < d1 * difference Then
            Return True
         Else
            Return False
         End If
      End If
   End Function

   Public Overloads Function GetHashCode(ByVal obj As Object) As Integer _
                    Implements IEqualityComparer.GetHashCode
      If TypeOf obj Is T1 Then
         Return CType(obj, T1).GetHashCode()
      ElseIf TypeOf obj Is T2 Then
         Return CType(obj, T2).GetHashCode()
      ElseIf TypeOf obj Is T3 Then
         Return CType(obj, T3).GetHashCode()
      ElseIf TypeOf obj Is T4 Then
         Return CType(obj, T4).GetHashCode()
      Else
         Return CType(obj, T5).GetHashCode()
      End If
   End Function
End Class

Module Example
   Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      Dim value1 = GetValues(1)
      Dim value2 = GetValues(2)
      Dim iValue1 As IStructuralEquatable = value1
      outputBlock.Text += String.Format("{0} ={3}{1} :{3}{2}", value1, value2, _
                        iValue1.Equals(value2, _
                        New DoubleComparer(Of Integer, Double, Double, Double, Double)(0.01)), _
                        vbCrLf) & vbCrLf
   End Sub

   Private Function GetValues(ByVal ctr As Integer) As Tuple(Of Integer, Double, Double, Double, Double)
      ' Generate four random numbers between 0 and 1
      Dim rnd As New Random(CInt((DateTime.Now.Ticks >> 32) >> ctr))
      Return Tuple.Create(ctr, rnd.NextDouble(), rnd.NextDouble(), _ 
                          rnd.NextDouble(), rnd.NextDouble)
   End Function
End Module
' The example displays output like the following:
'    (1, 0.910850029862882, 0.894596965934428, 0.319678635019659, 0.801647342649124) =
'    (2, 0.818546649915421, 0.355961162762698, 0.0438506622071614, 0.679904267042831) :
'    False
using System;
using System.Collections;

public class DoubleComparer<T1, T2, T3, T4, T5> : IEqualityComparer
{
   private double difference;
   private int argument = 0;

   public DoubleComparer(double difference)
   {
      this.difference = difference;
   }

   new public bool Equals(object x, object y)
   {
      argument += 1;

      // Return true for Item1.
      if (argument == 1) return true;

      double d1 = (double)x;
      double d2 = (double)y;

      if (d1 - d2 < d1 * difference)
         return true;
      else
         return false;
   }

   public int GetHashCode(object obj)
   {
      if (obj is T1)
         return ((T1)obj).GetHashCode();
      else if (obj is T2)
         return ((T2)obj).GetHashCode();
      else if (obj is T3)
         return ((T3)obj).GetHashCode();
      else if (obj is T4)
         return ((T4)obj).GetHashCode();
      else
         return ((T5)obj).GetHashCode();
   }
}

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      var value1 = GetValues(1);
      var value2 = GetValues(2);
      IStructuralEquatable iValue1 = value1;
      outputBlock.Text += String.Format("{0} =\n{1} :\n{2}", value1, value2,
                        iValue1.Equals(value2,
                        new DoubleComparer<int, double, double, double, double>(.01))) + "\n";
   }

   private static Tuple<int, double, double, double, double> GetValues(int ctr)
   {
      // Generate four random numbers between 0 and 1
      Random rnd = new Random((int)DateTime.Now.Ticks >> 32 >> ctr);
      return Tuple.Create(ctr, rnd.NextDouble(), rnd.NextDouble(),
                          rnd.NextDouble(), rnd.NextDouble());
   }
}

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.