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Double.Equals Method

  • Reference

Definition

Namespace:
System
Assembly:
System.Runtime.dll
Assembly:
mscorlib.dll
Assembly:
netstandard.dll

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:
 virtual bool Equals(double obj);
public bool Equals (double obj);
override this.Equals : double -> bool
Public Function Equals (obj As Double) As Boolean

Parameters

obj
Double

A Double object to compare to this instance.

Returns

Boolean

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

Implements

Equals(T)

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

let value = 112

let testObjectForEquality (obj: obj) =
    printfn $"{value} ({value.GetType().Name}) = {obj} ({obj.GetType().Name}): {value.Equals obj}\n"

let byte1 = 112uy
printfn $"value = byte1: {value.Equals byte1,16}"
testObjectForEquality byte1

let short1 = 112s
printfn $"value = short1: {value.Equals short1,16}"
testObjectForEquality short1

let int1 = 112
printfn $"value = int1: {value.Equals int1,18}"
testObjectForEquality int1

let long1 = 112L
printfn $"value = long1: {value.Equals long1,17}"
testObjectForEquality long1

let sbyte1 = 112y
printfn $"value = sbyte1: {value.Equals sbyte1,16}"
testObjectForEquality sbyte1

let ushort1 = 112us
printfn $"value = ushort1: {value.Equals ushort1,16}"
testObjectForEquality ushort1

let uint1 = 112u
printfn $"value = uint1: {value.Equals uint1,18}"
testObjectForEquality uint1

let ulong1 = 112uL
printfn $"value = ulong1: {value.Equals ulong1,17}"
testObjectForEquality ulong1

let dec1 = 112m
printfn $"value = dec1: {value.Equals dec1,21}"
testObjectForEquality dec1

let sng1 = 112f
printfn $"value = sng1: {value.Equals sng1,19}"
testObjectForEquality sng1

// 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

Module Example
   Dim value As Double = 112
   
   Public Sub Main()
      Dim byte1 As Byte = 112
      Console.WriteLine("value = byte1: {0,16}", value.Equals(byte1))
      TestObjectForEquality(byte1)
      
      Dim short1 As Short = 112
      Console.WriteLine("value = short1: {0,16}", value.Equals(short1))
      TestObjectForEquality(short1)

      Dim int1 As Integer = 112
      Console.WriteLine("value = int1: {0,18}", value.Equals(int1))
      TestObjectForEquality(int1)

      Dim long1 As Long = 112
      Console.WriteLine("value = long1: {0,17}", value.Equals(long1))
      TestObjectForEquality(long1)

      Dim sbyte1 As SByte = 112
      Console.WriteLine("value = sbyte1: {0,16}", value.Equals(sbyte1))
      TestObjectForEquality(sbyte1)
      
      Dim ushort1 As UShort = 112
      Console.WriteLine("value = ushort1: {0,16}", value.Equals(ushort1))
      TestObjectForEquality(ushort1)

      Dim uint1 As UInteger = 112
      Console.WriteLine("value = uint1: {0,18}", value.Equals(uint1))
      TestObjectForEquality(uint1)

      Dim ulong1 As ULong = 112
      Console.WriteLine("value = ulong1: {0,17}", value.Equals(ulong1))
      TestObjectForEquality(ulong1)
      
      Dim dec1 As Decimal = 112d
      Console.WriteLine("value = dec1: {0,20}", value.Equals(dec1))
      TestObjectForEquality(dec1)

      Dim sng1 As Single = 112
      Console.WriteLine("value = sng1: {0,19}", value.Equals(sng1))
      TestObjectForEquality(sng1)
   End Sub
   
   Private Sub TestObjectForEquality(obj As Object)
      Console.WriteLine("{0} ({1}) = {2} ({3}): {4}",
                        value, value.GetType().Name,
                        obj, obj.GetType().Name,
                        value.Equals(obj))
      Console.WriteLine()
   End Sub
End Module
' 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:                 True
'       112 (Double) = 112 (Decimal): False
'
'       value = sng1:                True
'       112 (Double) = 112 (Single): False

See also

Applies to

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(System::Object ^ obj);
public override bool Equals (object obj);
public override bool Equals (object? obj);
override this.Equals : obj -> bool
Public Overrides Function Equals (obj As Object) As Boolean

Parameters

obj
Object

An object to compare with this instance.

Returns

Boolean

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

// Initialize two doubles with apparently identical values
let double1 = 0.33333
let double2 = double (1 / 3) |> box
// Compare them for equality
printfn $"{double1.Equals double2}"    // displays false

' Initialize two doubles with apparently identical values
Dim double1 As Double = .33333
Dim double2 As Object = 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.

Note

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

let value = 112

let testObjectForEquality (obj: obj) =
    printfn $"{value} ({value.GetType().Name}) = {obj} ({obj.GetType().Name}): {value.Equals obj}\n"

let byte1 = 112uy
printfn $"value = byte1: {value.Equals byte1,16}"
testObjectForEquality byte1

let short1 = 112s
printfn $"value = short1: {value.Equals short1,16}"
testObjectForEquality short1

let int1 = 112
printfn $"value = int1: {value.Equals int1,18}"
testObjectForEquality int1

let long1 = 112L
printfn $"value = long1: {value.Equals long1,17}"
testObjectForEquality long1

let sbyte1 = 112y
printfn $"value = sbyte1: {value.Equals sbyte1,16}"
testObjectForEquality sbyte1

let ushort1 = 112us
printfn $"value = ushort1: {value.Equals ushort1,16}"
testObjectForEquality ushort1

let uint1 = 112u
printfn $"value = uint1: {value.Equals uint1,18}"
testObjectForEquality uint1

let ulong1 = 112uL
printfn $"value = ulong1: {value.Equals ulong1,17}"
testObjectForEquality ulong1

let dec1 = 112m
printfn $"value = dec1: {value.Equals dec1,21}"
testObjectForEquality dec1

let sng1 = 112f
printfn $"value = sng1: {value.Equals sng1,19}"
testObjectForEquality sng1

// 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

Module Example
   Dim value As Double = 112
   
   Public Sub Main()
      Dim byte1 As Byte = 112
      Console.WriteLine("value = byte1: {0,16}", value.Equals(byte1))
      TestObjectForEquality(byte1)
      
      Dim short1 As Short = 112
      Console.WriteLine("value = short1: {0,16}", value.Equals(short1))
      TestObjectForEquality(short1)

      Dim int1 As Integer = 112
      Console.WriteLine("value = int1: {0,18}", value.Equals(int1))
      TestObjectForEquality(int1)

      Dim long1 As Long = 112
      Console.WriteLine("value = long1: {0,17}", value.Equals(long1))
      TestObjectForEquality(long1)

      Dim sbyte1 As SByte = 112
      Console.WriteLine("value = sbyte1: {0,16}", value.Equals(sbyte1))
      TestObjectForEquality(sbyte1)
      
      Dim ushort1 As UShort = 112
      Console.WriteLine("value = ushort1: {0,16}", value.Equals(ushort1))
      TestObjectForEquality(ushort1)

      Dim uint1 As UInteger = 112
      Console.WriteLine("value = uint1: {0,18}", value.Equals(uint1))
      TestObjectForEquality(uint1)

      Dim ulong1 As ULong = 112
      Console.WriteLine("value = ulong1: {0,17}", value.Equals(ulong1))
      TestObjectForEquality(ulong1)
      
      Dim dec1 As Decimal = 112d
      Console.WriteLine("value = dec1: {0,20}", value.Equals(dec1))
      TestObjectForEquality(dec1)

      Dim sng1 As Single = 112
      Console.WriteLine("value = sng1: {0,19}", value.Equals(sng1))
      TestObjectForEquality(sng1)
   End Sub
   
   Private Sub TestObjectForEquality(obj As Object)
      Console.WriteLine("{0} ({1}) = {2} ({3}): {4}",
                        value, value.GetType().Name,
                        obj, obj.GetType().Name,
                        value.Equals(obj))
      Console.WriteLine()
   End Sub
End Module
' 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:                 True
'       112 (Double) = 112 (Decimal): False
'
'       value = sng1:                True
'       112 (Double) = 112 (Single): False

See also

Applies to