Tuple<T1,T2,T3,T4,T5,T6>.IStructuralEquatable.Equals Method

Definition

Namespace:

System

Assemblies:

netstandard.dll, System.Runtime.dll

Source:

Tuple.cs

Returns a value that indicates whether the current Tuple<T1,T2,T3,T4,T5,T6> object is equal to a specified object based on a specified comparison method.

C#

bool IStructuralEquatable.Equals(object other, System.Collections.IEqualityComparer comparer);

Parameters

other

Object

The object to compare with this instance.

comparer

IEqualityComparer

An object that defines the method to use to evaluate whether the two objects are equal.

Returns

Boolean

true if the current instance is equal to the specified object; otherwise, false.

Implements

Equals(Object, IEqualityComparer)

Examples

The following example defines a RateComparer class that performs a custom test for equality. If the values that are passed to its IStructuralEquatable.Equals method are of type Single or Double, the method tests for equality by using only up to three fractional digits. Otherwise, it simply calls the x parameter's Equals method. The example uses this IEqualityComparer implementation to determine whether four Tuple<T1,T2,T3,T4,T5,T6> objects that contain data on the rate of population change between 1960 and 2000 are equal.

C#

using System;
using System.Collections;

public class RateComparer<T1, T2, T3, T4, T5, T6> : IEqualityComparer
{
   private int argument = 0;

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

      double fx, fy; 
      if (x is Double || x is Single)
      {
            fx = (double) x;
            fy = (double) y;
            return Math.Round(fx * 1000).Equals(Math.Round(fy * 1000));
      }
      else
      {
         return x.Equals(y);
      }
   }
   
   public int GetHashCode(object obj)
   {
      if (obj is Single || obj is Double)
         return Math.Round(((double) obj) * 1000).GetHashCode();
      else
         return obj.GetHashCode();
   }                
}

public class Example
{
   public static void Main()
   {
      var rate1 = Tuple.Create("New York", .014505, -.1042733, 
                               .0354833, .093644, .0290792);
      var rate2 = Tuple.Create("Unknown City", .014505, -.1042733, 
                               .0354833, .093644, .0290792);
      var rate3 = Tuple.Create("Unknown City", .014505, -.1042733, 
                               .0354833, .093644, .029079);
      var rate4 = Tuple.Create("San Francisco", -.0332858, -.0512803, 
                               .0662544, .0728964, .0491912);
      IStructuralEquatable eq = rate1;
      // Compare first tuple with remaining two tuples.
      Console.WriteLine("{0} = ", rate1.ToString());
      Console.WriteLine("   {0} : {1}", rate2, 
                        eq.Equals(rate2, new RateComparer<string, double, double, double, double, double>()));
      Console.WriteLine("   {0} : {1}", rate3, 
                        eq.Equals(rate3, new RateComparer<string, double, double, double, double, double>()));
      Console.WriteLine("   {0} : {1}", rate4, 
                        eq.Equals(rate4, new RateComparer<string, double, double, double, double, double>()));
   }
}
// The example displays the following output:
//    (New York, 0.014505, -0.1042733, 0.0354833, 0.093644, 0.0290792) =
//       (Unknown City, 0.014505, -0.1042733, 0.0354833, 0.093644, 0.0290792) : True
//       (Unknown City, 0.014505, -0.1042733, 0.0354833, 0.093644, 0.029079) : True
//       (San Francisco, -0.0332858, -0.0512803, 0.0662544, 0.0728964, 0.0491912) : False

Remarks

This member is an explicit interface member implementation. It can be used only when the Tuple<T1,T2,T3,T4,T5,T6> 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,T6> 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,T6> 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,T6> objects. This continues until the method call returns false when it compares a specific pair of Item values, or the two Item6 values are passed to the method.

Applies to