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

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)

bool IStructuralEquatable.Equals(
	Object other,
	IEqualityComparer comparer


Type: System.Object
The object to compare with this instance.
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.


IStructuralEquatable.Equals(Object, IEqualityComparer)

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 null, 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.

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.

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;
         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();
         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,
                        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());


Supported in: 5, 4

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