Double Structure

Represents a double-precision floating-point number.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)

[SerializableAttribute]
[ComVisibleAttribute(true)]
public value class Double : IComparable, 
	IFormattable, IConvertible, IComparable<double>, IEquatable<double>

The Double type exposes the following members.

  NameDescription
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryCompareTo(Double)Compares this instance to a specified double-precision floating-point number and returns an integer that indicates whether the value of this instance is less than, equal to, or greater than the value of the specified double-precision floating-point number.
Public methodSupported by the XNA FrameworkCompareTo(Object)Compares this instance to a specified object and returns an integer that indicates whether the value of this instance is less than, equal to, or greater than the value of the specified object.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryEquals(Double)Returns a value indicating whether this instance and a specified Double object represent the same value.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryEquals(Object)Returns a value indicating whether this instance is equal to a specified object. (Overrides ValueType::Equals(Object).)
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibraryFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGetHashCodeReturns the hash code for this instance. (Overrides ValueType::GetHashCode().)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodSupported by the XNA FrameworkGetTypeCodeReturns the TypeCode for value type Double.
Public methodStatic memberSupported by the XNA FrameworkSupported by Portable Class LibraryIsInfinityReturns a value indicating whether the specified number evaluates to negative or positive infinity
Public methodStatic memberSupported by the XNA FrameworkSupported by Portable Class LibraryIsNaNReturns a value indicating whether the specified number evaluates to a value that is not a number (NaN).
Public methodStatic memberSupported by the XNA FrameworkSupported by Portable Class LibraryIsNegativeInfinityReturns a value indicating whether the specified number evaluates to negative infinity.
Public methodStatic memberSupported by the XNA FrameworkSupported by Portable Class LibraryIsPositiveInfinityReturns a value indicating whether the specified number evaluates to positive infinity.
Protected methodSupported by the XNA FrameworkSupported by Portable Class LibraryMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodStatic memberSupported by the XNA FrameworkParse(String)Converts the string representation of a number to its double-precision floating-point number equivalent.
Public methodStatic memberSupported by the XNA FrameworkParse(String, NumberStyles)Converts the string representation of a number in a specified style to its double-precision floating-point number equivalent.
Public methodStatic memberSupported by the XNA FrameworkSupported by Portable Class LibraryParse(String, IFormatProvider)Converts the string representation of a number in a specified culture-specific format to its double-precision floating-point number equivalent.
Public methodStatic memberSupported by the XNA FrameworkSupported by Portable Class LibraryParse(String, NumberStyles, IFormatProvider)Converts the string representation of a number in a specified style and culture-specific format to its double-precision floating-point number equivalent.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryToString()Converts the numeric value of this instance to its equivalent string representation. (Overrides ValueType::ToString().)
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryToString(IFormatProvider)Converts the numeric value of this instance to its equivalent string representation using the specified culture-specific format information.
Public methodSupported by the XNA FrameworkToString(String)Converts the numeric value of this instance to its equivalent string representation, using the specified format.
Public methodSupported by the XNA FrameworkSupported by Portable Class LibraryToString(String, IFormatProvider)Converts the numeric value of this instance to its equivalent string representation using the specified format and culture-specific format information.
Public methodStatic memberTryParse(String, Double%)Converts the string representation of a number to its double-precision floating-point number equivalent. A return value indicates whether the conversion succeeded or failed.
Public methodStatic memberSupported by Portable Class LibraryTryParse(String, NumberStyles, IFormatProvider, Double%)Converts the string representation of a number in a specified style and culture-specific format to its double-precision floating-point number equivalent. A return value indicates whether the conversion succeeded or failed.
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  NameDescription
Public operatorStatic memberEqualityReturns a value that indicates whether two specified Double values are equal.
Public operatorStatic memberGreaterThanReturns a value that indicates whether a specified Double value is greater than another specified Double value.
Public operatorStatic memberGreaterThanOrEqualReturns a value that indicates whether a specified Double value is greater than or equal to another specified Double value.
Public operatorStatic memberInequalityReturns a value that indicates whether two specified Double values are not equal.
Public operatorStatic memberLessThanReturns a value that indicates whether a specified Double value is less than another specified Double value.
Public operatorStatic memberLessThanOrEqualReturns a value that indicates whether a specified Double value is less than or equal to another specified Double value.
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  NameDescription
Public fieldStatic memberSupported by the XNA FrameworkSupported by Portable Class LibraryEpsilonRepresents the smallest positive Double value that is greater than zero. This field is constant.
Public fieldStatic memberSupported by the XNA FrameworkSupported by Portable Class LibraryMaxValueRepresents the largest possible value of a Double. This field is constant.
Public fieldStatic memberSupported by the XNA FrameworkSupported by Portable Class LibraryMinValueRepresents the smallest possible value of a Double. This field is constant.
Public fieldStatic memberSupported by the XNA FrameworkSupported by Portable Class LibraryNaNRepresents a value that is not a number (NaN). This field is constant.
Public fieldStatic memberSupported by the XNA FrameworkSupported by Portable Class LibraryNegativeInfinityRepresents negative infinity. This field is constant.
Public fieldStatic memberSupported by the XNA FrameworkSupported by Portable Class LibraryPositiveInfinityRepresents positive infinity. This field is constant.
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  NameDescription
Explicit interface implemetationPrivate methodSupported by the XNA FrameworkIConvertible::ToBooleanInfrastructure. For a description of this member, see IConvertible::ToBoolean.
Explicit interface implemetationPrivate methodSupported by the XNA FrameworkIConvertible::ToByteInfrastructure. For a description of this member, see IConvertible::ToByte.
Explicit interface implemetationPrivate methodSupported by the XNA FrameworkIConvertible::ToCharInfrastructure. This conversion is not supported. Attempting to use this method throws an InvalidCastException.
Explicit interface implemetationPrivate methodSupported by the XNA FrameworkIConvertible::ToDateTimeInfrastructure. This conversion is not supported. Attempting to use this method throws an InvalidCastException
Explicit interface implemetationPrivate methodSupported by the XNA FrameworkIConvertible::ToDecimalInfrastructure. For a description of this member, see IConvertible::ToDecimal.
Explicit interface implemetationPrivate methodSupported by the XNA FrameworkIConvertible::ToDoubleInfrastructure. For a description of this member, see IConvertible::ToDouble.
Explicit interface implemetationPrivate methodSupported by the XNA FrameworkIConvertible::ToInt16Infrastructure. For a description of this member, see IConvertible::ToInt16.
Explicit interface implemetationPrivate methodSupported by the XNA FrameworkIConvertible::ToInt32Infrastructure. For a description of this member, see IConvertible::ToInt32.
Explicit interface implemetationPrivate methodSupported by the XNA FrameworkIConvertible::ToInt64Infrastructure. For a description of this member, see IConvertible::ToInt64.
Explicit interface implemetationPrivate methodSupported by the XNA FrameworkIConvertible::ToSByteInfrastructure. For a description of this member, see IConvertible::ToSByte.
Explicit interface implemetationPrivate methodSupported by the XNA FrameworkIConvertible::ToSingleInfrastructure. For a description of this member, see IConvertible::ToSingle.
Explicit interface implemetationPrivate methodSupported by the XNA FrameworkIConvertible::ToTypeInfrastructure. For a description of this member, see IConvertible::ToType.
Explicit interface implemetationPrivate methodSupported by the XNA FrameworkIConvertible::ToUInt16Infrastructure. For a description of this member, see IConvertible::ToUInt16.
Explicit interface implemetationPrivate methodSupported by the XNA FrameworkIConvertible::ToUInt32Infrastructure. For a description of this member, see IConvertible::ToUInt32.
Explicit interface implemetationPrivate methodSupported by the XNA FrameworkIConvertible::ToUInt64Infrastructure. For a description of this member, see IConvertible::ToUInt64.
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The Double value type represents a double-precision 64-bit number with values ranging from negative 1.79769313486232e308 to positive 1.79769313486232e308, as well as positive or negative zero, PositiveInfinity, NegativeInfinity, and Not-a-Number (NaN).

Double complies with the IEC 60559:1989 (IEEE 754) standard for binary floating-point arithmetic.

Double provides methods to compare instances of this type, convert the value of an instance to its string representation, and convert the string representation of a number to an instance of this type. For information about how format specification codes control the string representation of value types, see Formatting Types, Standard Numeric Format Strings, and Custom Numeric Format Strings.

Using Floating-Point Numbers

When performing binary operations, if one of the operands is a Double, then the other operand is required to be an integral type or a floating-point type (Double or Single). Prior to performing the operation, if the other operand is not a Double, it is converted to Double, and the operation is performed using at least Double range and precision. If the operation produces a numeric result, the type of the result is Double.

The floating-point operators, including the assignment operators, do not throw exceptions. Instead, in exceptional situations the result of a floating-point operation is zero, infinity, or NaN, as described below:

  • If the result of a floating-point operation is too small for the destination format, the result of the operation is zero.

  • If the magnitude of the result of a floating-point operation is too large for the destination format, the result of the operation is PositiveInfinity or NegativeInfinity, as appropriate for the sign of the result.

  • If a floating-point operation is invalid, the result of the operation is NaN.

  • If one or both operands of a floating-point operation are NaN, the result of the operation is NaN.

Floating-Point Values and Loss of Precision

Remember that a floating-point number can only approximate a decimal number, and that the precision of a floating-point number determines how accurately that number approximates a decimal number. By default, a Double value contains 15 decimal digits of precision, although a maximum of 17 digits is maintained internally. The precision of a floating-point number has several consequences:

  • Two floating-point numbers that appear equal for a particular precision might not compare equal because their least significant digits are different.

  • A mathematical or comparison operation that uses a floating-point number might not yield the same result if a decimal number is used because the floating-point number might not exactly approximate the decimal number.

  • A value might not roundtrip if a floating-point number is involved. A value is said to roundtrip if an operation converts an original floating-point number to another form, an inverse operation transforms the converted form back to a floating-point number, and the final floating-point number is equal to the original floating-point number. The roundtrip might fail because one or more least significant digits are lost or changed in a conversion.

In addition, the result of arithmetic and assignment operations with Double values may differ slightly by platform because of the loss of precision of the Double type. For example, the result of assigning a literal Double value may differ in the 32-bit and 64-bit versions of the .NET Framework. The following example illustrates this difference when the literal value -4.42330604244772E-305 and a variable whose value is -4.42330604244772E-305 are assigned to a Double variable. Note that the result of the Parse(String) method in this case does not suffer from a loss of precision.

No code example is currently available or this language may not be supported.

The following code example illustrates the use of Double:


// The Temperature class stores the temperature as a Double
// and delegates most of the functionality to the Double 
// implementation.
public ref class Temperature: public IComparable, public IFormattable
{
   // IComparable.CompareTo implementation.
public:
   virtual int CompareTo( Object^ obj )
   {
      if (obj == nullptr) return 1;

      if (dynamic_cast<Temperature^>(obj) )
      {
         Temperature^ temp = (Temperature^)(obj);
         return m_value.CompareTo( temp->m_value );
      }
      throw gcnew ArgumentException( "object is not a Temperature" );
   }

   // IFormattable.ToString implementation.
   virtual String^ ToString( String^ format, IFormatProvider^ provider )
   {
      if ( format != nullptr )
      {
         if ( format->Equals( "F" ) )
         {
            return String::Format( "{0}'F", this->Value.ToString() );
         }

         if ( format->Equals( "C" ) )
         {
            return String::Format( "{0}'C", this->Celsius.ToString() );
         }
      }
      return m_value.ToString( format, provider );
   }

   // Parses the temperature from a string in the form
   // [ws][sign]digits['F|'C][ws]
   static Temperature^ Parse( String^ s, NumberStyles styles, IFormatProvider^ provider )
   {
      Temperature^ temp = gcnew Temperature;

      if ( s->TrimEnd(nullptr)->EndsWith( "'F" ) )
      {
         temp->Value = Double::Parse( s->Remove( s->LastIndexOf( '\'' ), 2 ), styles, provider );
      }
      else
      if ( s->TrimEnd(nullptr)->EndsWith( "'C" ) )
      {
         temp->Celsius = Double::Parse( s->Remove( s->LastIndexOf( '\'' ), 2 ), styles, provider );
      }
      else
      {
         temp->Value = Double::Parse( s, styles, provider );
      }
      return temp;
   }

protected:
   double m_value;

public:
   property double Value 
   {
      double get()
      {
         return m_value;
      }

      void set( double value )
      {
         m_value = value;
      }
   }

   property double Celsius 
   {
      double get()
      {
         return (m_value - 32.0) / 1.8;
      }

      void set( double value )
      {
         m_value = 1.8 * value + 32.0;
      }
   }
};


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

All members of this type are thread safe. Members that appear to modify instance state actually return a new instance initialized with the new value. As with any other type, reading and writing to a shared variable that contains an instance of this type must be protected by a lock to guarantee thread safety.

Caution noteCaution

Assigning an instance of this type is not thread safe on all hardware platforms because the binary representation of that instance might be too large to assign in a single atomic operation.

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