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Tuple<T1>.IStructuralEquatable.Equals Method

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)

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

IStructuralEquatable.Equals(Object, IEqualityComparer)

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 null, 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.

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).


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


Silverlight

Supported in: 5, 4

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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