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Double.Equals Method

Definition

Returns a value indicating whether two instances of Double represent the same value.

Overloads

Equals(Double)

Returns a value indicating whether this instance and a specified Double object represent the same value.

Equals(Object)

Returns a value indicating whether this instance is equal to a specified object.

Equals(Double)

Source:
Double.cs
Source:
Double.cs
Source:
Double.cs

Returns a value indicating whether this instance and a specified Double object represent the same value.

public bool Equals (double obj);

Parameters

obj
Double

A Double object to compare to this instance.

Returns

true if obj is equal to this instance; otherwise, false.

Implements

Remarks

For more information about this API, see Supplemental API remarks for Double.Equals.

Notes to Callers

Compiler overload resolution may account for an apparent difference in the behavior of the two Equals(Object) method overloads. If an implicit conversion between the obj argument and a Double is defined and the argument is not typed as an Object, compilers may perform an implicit conversion and call the Equals(Double) method. Otherwise, they call the Equals(Object) method, which always returns false if its obj argument is not a 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 Decimal and in C#, the first comparison returns true because the compiler automatically performs a widening conversion and calls the Equals(Double) method, whereas the second comparison returns false because the compiler calls the Equals(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));
      TestObjectForEquality(byte1);

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

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

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

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

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

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

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

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

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

   private static void TestObjectForEquality(Object obj)
   {
      Console.WriteLine("{0} ({1}) = {2} ({3}): {4}\n",
                        value, value.GetType().Name,
                        obj, obj.GetType().Name,
                        value.Equals(obj));
   }
}
// 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

See also

Applies to

.NET 9 en andere versies
Product Versies
.NET Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9
.NET Framework 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 2.0, 2.1
UWP 10.0

Equals(Object)

Source:
Double.cs
Source:
Double.cs
Source:
Double.cs

Returns a value indicating whether this instance is equal to a specified object.

public override bool Equals (object obj);
public override bool Equals (object? obj);

Parameters

obj
Object

An object to compare with this instance.

Returns

true if obj is an instance of Double and equals the value of this instance; otherwise, false.

Remarks

The Equals 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 Double value .3333 and the Double returned by dividing 1 by 3 are unequal.

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

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

Notitie

Because 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 Epsilon. Typically, it is many times greater than 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 Double.NaN values are tested for equality by calling the Equals method, the method returns true. However, if two 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 Double is not a number (NaN), an alternative is to call the IsNaN method.

Notes to Callers

Compiler overload resolution may account for an apparent difference in the behavior of the two Equals(Object) method overloads. If an implicit conversion between the obj argument and a Double is defined and the argument is not typed as an Object, compilers may perform an implicit conversion and call the Equals(Double) method. Otherwise, they call the Equals(Object) method, which always returns false if its obj argument is not a 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 Decimal and in C#, the first comparison returns true because the compiler automatically performs a widening conversion and calls the Equals(Double) method, whereas the second comparison returns false because the compiler calls the Equals(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));
      TestObjectForEquality(byte1);

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

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

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

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

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

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

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

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

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

   private static void TestObjectForEquality(Object obj)
   {
      Console.WriteLine("{0} ({1}) = {2} ({3}): {4}\n",
                        value, value.GetType().Name,
                        obj, obj.GetType().Name,
                        value.Equals(obj));
   }
}
// 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

See also

Applies to

.NET 9 en andere versies
Product Versies
.NET Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9
.NET Framework 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 2.0, 2.1
UWP 10.0