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Método Double.Equals (Object)


Publicado: octubre de 2016

Devuelve un valor que indica si esta instancia equivale a un objeto especificado.

Espacio de nombres:   System
Ensamblado:  mscorlib (en mscorlib.dll)

public override bool Equals(
	object obj


Type: System.Object

Objeto que se va a comparar con esta instancia.

Valor devuelto

Type: System.Boolean

Es true si obj es una instancia de Double y es igual al valor de esta instancia; en caso contrario, es false.

TheM:System.Double.Equals(System.Double) method should be used with caution, because two apparently equivalent values can be unequal due to the differing precision of the two values. The following example reports that the T:System.Double value .3333 and the T:System.Double returned by dividing 1 by 3 are unequal.

// Initialize two doubles with apparently identical values
double double1 = .33333;
object double2 = 1/3;
// Compare them for equality
Console.WriteLine(double1.Equals(double2));    // displays false

For alternatives to calling the M:System.Double.Equals(System.Object) method, see the documentation for the M:System.Double.Equals(System.Double) overload.


Because F:System.Double.Epsilon defines the minimum expression of a positive value whose range is near zero, the margin of difference between two similar values must be greater than F:System.Double.Epsilon. Typically, it is many times greater than F:System.Double.Epsilon.

The precision of floating-point numbers beyond the documented precision is specific to the implementation and version of the .NET Framework. Consequently, a comparison of two particular numbers might change between versions of the .NET Framework because the precision of the numbers' internal representation might change.

If two F:System.Double.NaN values are tested for equality by calling the M:System.Double.Equals(System.Double) method, the method returns true. However, if two F:System.Double.NaN values are tested for equality by using the equality operator, the operator returns false. When you want to determine whether the value of a T:System.Double is not a number (NaN), an alternative is to call the M:System.Double.IsNaN(System.Double) method.

Notas para llamadores:

Compiler overload resolution may account for an apparent difference in the behavior of the two M:System.Double.Equals(System.Object) method overloads. If an implicit conversion between the obj argument and a T:System.Double is defined and the argument is not typed as an T:System.Object, compilers may perform an implicit conversion and call the M:System.Double.Equals(System.Double) method. Otherwise, they call the M:System.Double.Equals(System.Object) method, which always returns false if its obj argument is not a T:System.Double value. The following example illustrates the difference in behavior between the two method overloads. In the case of all primitive numeric types except for T:System.Decimal and in C#, the first comparison returns true because the compiler automatically performs a widening conversion and calls the M:System.Double.Equals(System.Double) method, whereas the second comparison returns false because the compiler calls the M:System.Double.Equals(System.Object) method.

using System;

public class Example
   static double value = 112;

   public static void Main()
      byte byte1= 112;
      Console.WriteLine("value = byte1: {0,16}", value.Equals(byte1));

      short short1 = 112;
      Console.WriteLine("value = short1: {0,16}", value.Equals(short1));

      int int1 = 112;
      Console.WriteLine("value = int1: {0,18}", value.Equals(int1));

      long long1 = 112;
      Console.WriteLine("value = long1: {0,17}", value.Equals(long1));

      sbyte sbyte1 = 112;
      Console.WriteLine("value = sbyte1: {0,16}", value.Equals(sbyte1));

      ushort ushort1 = 112;
      Console.WriteLine("value = ushort1: {0,16}", value.Equals(ushort1));

      uint uint1 = 112;
      Console.WriteLine("value = uint1: {0,18}", value.Equals(uint1));

      ulong ulong1 = 112;
      Console.WriteLine("value = ulong1: {0,17}", value.Equals(ulong1));

      decimal dec1 = 112m;
      Console.WriteLine("value = dec1: {0,21}", value.Equals(dec1));

      float sng1 = 112;
      Console.WriteLine("value = sng1: {0,19}", value.Equals(sng1));

   private static void TestObjectForEquality(Object obj)
      Console.WriteLine("{0} ({1}) = {2} ({3}): {4}\n",
                        value, value.GetType().Name,
                        obj, obj.GetType().Name,
// The example displays the following output:
//       value = byte1:             True
//       112 (Double) = 112 (Byte): False
//       value = short1:             True
//       112 (Double) = 112 (Int16): False
//       value = int1:               True
//       112 (Double) = 112 (Int32): False
//       value = long1:              True
//       112 (Double) = 112 (Int64): False
//       value = sbyte1:             True
//       112 (Double) = 112 (SByte): False
//       value = ushort1:             True
//       112 (Double) = 112 (UInt16): False
//       value = uint1:               True
//       112 (Double) = 112 (UInt32): False
//       value = ulong1:              True
//       112 (Double) = 112 (UInt64): False
//       value = dec1:                 False
//       112 (Double) = 112 (Decimal): False
//       value = sng1:                True
//       112 (Double) = 112 (Single): False

Plataforma universal de Windows
Disponible desde 8
.NET Framework
Disponible desde 1.1
Biblioteca de clases portable
Se admite en: plataformas portátiles de .NET
Disponible desde 2.0
Windows Phone Silverlight
Disponible desde 7.0
Windows Phone
Disponible desde 8.1
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