Represents a double-precision floating-point number.
Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Visual Basic (Declaration)
<SerializableAttribute> _
<ComVisibleAttribute(True)> _
Public Structure Double
Implements IComparable, IFormattable, IConvertible, IComparable(Of Double), _
IEquatable(Of Double)
[SerializableAttribute]
[ComVisibleAttribute(true)]
public struct Double : IComparable, IFormattable, IConvertible,
IComparable<double>, IEquatable<double>
[SerializableAttribute]
[ComVisibleAttribute(true)]
public value class Double : IComparable, IFormattable, IConvertible,
IComparable<double>, IEquatable<double>
/** @attribute SerializableAttribute() */
/** @attribute ComVisibleAttribute(true) */
public final class Double extends ValueType implements IComparable, IFormattable,
IConvertible, IComparable<double>, IEquatable<double>
JScript suports the use of structures, but not the declaration of new ones.
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 Overview, 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.
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.
Interface Implementations
The following code example illustrates the use of Double:
' Temperature class stores the value as Double
' and delegates most of the functionality
' to the Double implementation.
Public Class Temperature
Implements IComparable, IFormattable
Public Overloads Function CompareTo(ByVal obj As Object) As Integer _
Implements IComparable.CompareTo
If TypeOf obj Is Temperature Then
Dim temp As Temperature = CType(obj, Temperature)
Return m_value.CompareTo(temp.m_value)
End If
Throw New ArgumentException("object is not a Temperature")
End Function
Public Overloads Function ToString(ByVal format As String, ByVal provider As IFormatProvider) As String _
Implements IFormattable.ToString
If Not (format Is Nothing) Then
If format.Equals("F") Then
Return [String].Format("{0}'F", Me.Value.ToString())
End If
If format.Equals("C") Then
Return [String].Format("{0}'C", Me.Celsius.ToString())
End If
End If
Return m_value.ToString(format, provider)
End Function
' Parses the temperature from a string in form
' [ws][sign]digits['F|'C][ws]
Public Shared Function Parse(ByVal s As String, ByVal styles As NumberStyles, ByVal provider As IFormatProvider) As Temperature
Dim temp As New Temperature()
If s.TrimEnd(Nothing).EndsWith("'F") Then
temp.Value = Double.Parse(s.Remove(s.LastIndexOf("'"c), 2), styles, provider)
Else
If s.TrimEnd(Nothing).EndsWith("'C") Then
temp.Celsius = Double.Parse(s.Remove(s.LastIndexOf("'"c), 2), styles, provider)
Else
temp.Value = Double.Parse(s, styles, provider)
End If
End If
Return temp
End Function
' The value holder
Protected m_value As Double
Public Property Value() As Double
Get
Return m_value
End Get
Set(ByVal Value As Double)
m_value = Value
End Set
End Property
Public Property Celsius() As Double
Get
Return (m_value - 32) / 1.8
End Get
Set(ByVal Value As Double)
m_value = Value * 1.8 + 32
End Set
End Property
End Class
/// <summary>
/// Temperature class stores the value as Double
/// and delegates most of the functionality
/// to the Double implementation.
/// </summary>
public class Temperature : IComparable, IFormattable {
/// <summary>
/// IComparable.CompareTo implementation.
/// </summary>
public int CompareTo(object obj) {
if(obj is Temperature) {
Temperature temp = (Temperature) obj;
return m_value.CompareTo(temp.m_value);
}
throw new ArgumentException("object is not a Temperature");
}
/// <summary>
/// IFormattable.ToString implementation.
/// </summary>
public string ToString(string format, IFormatProvider provider) {
if( format != null ) {
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);
}
/// <summary>
/// Parses the temperature from a string in form
/// [ws][sign]digits['F|'C][ws]
/// </summary>
public static Temperature Parse(string s, NumberStyles styles, IFormatProvider provider) {
Temperature temp = new Temperature();
if( s.TrimEnd(null).EndsWith("'F") ) {
temp.Value = Double.Parse( s.Remove(s.LastIndexOf('\''), 2), styles, provider);
}
else if( s.TrimEnd(null).EndsWith("'C") ) {
temp.Celsius = Double.Parse( s.Remove(s.LastIndexOf('\''), 2), styles, provider);
}
else {
temp.Value = Double.Parse(s, styles, provider);
}
return temp;
}
// The value holder
protected double m_value;
public double Value {
get {
return m_value;
}
set {
m_value = value;
}
}
public double Celsius {
get {
return (m_value-32.0)/1.8;
}
set {
m_value = 1.8*value+32.0;
}
}
}
/// <summary>
/// Temperature class stores the value as Double
/// and delegates most of the functionality
/// to the Double implementation.
/// </summary>
public ref class Temperature: public IComparable, public IFormattable
{
/// <summary>
/// IComparable.CompareTo implementation.
/// </summary>
public:
virtual int CompareTo( Object^ obj )
{
if ( dynamic_cast<Temperature^>(obj) )
{
Temperature^ temp = (Temperature^)(obj);
return m_value.CompareTo( temp->m_value );
}
throw gcnew ArgumentException( "object is not a Temperature" );
}
/// <summary>
/// IFormattable.ToString implementation.
/// </summary>
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 );
}
/// <summary>
/// Parses the temperature from a string in form
/// [ws][sign]digits['F|'C][ws]
/// </summary>
static Temperature^ Parse( String^ s, NumberStyles styles, IFormatProvider^ provider )
{
Temperature^ temp = gcnew Temperature;
if ( s->TrimEnd( 0 )->EndsWith( "'F" ) )
{
temp->Value = Double::Parse( s->Remove( s->LastIndexOf( '\'' ), 2 ), styles, provider );
}
else
if ( s->TrimEnd( 0 )->EndsWith( "'C" ) )
{
temp->Celsius = Double::Parse( s->Remove( s->LastIndexOf( '\'' ), 2 ), styles, provider );
}
else
{
temp->Value = Double::Parse( s, styles, provider );
}
return temp;
}
protected:
// The value holder
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;
}
}
};
/// <summary>
/// Temperature class stores the value as Double
/// and delegates most of the functionality
/// to the Double implementation.
/// </summary>
public class Temperature implements IComparable, IFormattable {
/// <summary>
/// IComparable.CompareTo implementation.
/// </summary>
public function CompareTo(obj) : int{
if(obj.GetType() == Temperature) {
var temp : Temperature = Temperature(obj);
return m_value.CompareTo(temp.m_value);
}
throw new ArgumentException("object is not a Temperature");
}
/// <summary>
/// IFormattable.ToString implementation.
/// </summary>
public function ToString(format : String, provider : IFormatProvider) : String {
if( format != null ) {
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);
}
/// <summary>
/// Parses the temperature from a string in form
/// [ws][sign]digits['F|'C][ws]
/// </summary>
public static function Parse(s : String, styles : NumberStyles, provider : IFormatProvider) : Temperature{
var temp : Temperature = new Temperature();
if( s.TrimEnd(null).EndsWith("'F") ) {
temp.Value = Double.Parse( s.Remove(s.LastIndexOf('\''), 2), styles, provider);
}
else if( s.TrimEnd(null).EndsWith("'C") ) {
temp.Celsius = Double.Parse( s.Remove(s.LastIndexOf('\''), 2), styles, provider);
}
else {
temp.Value = Double.Parse(s, styles, provider);
}
return temp;
}
// The value holder
protected var m_value : double;
public function get Value() : double{
return m_value;
}
public function set Value(value : double) {
m_value = value;
}
public function get Celsius() : double {
return (m_value-32.0)/1.8;
}
public function set Celsius(value : double) {
m_value = 1.8*value+32.0;
}
}
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.
.NET Framework
Supported in: 2.0, 1.1, 1.0
.NET Compact Framework
Supported in: 2.0, 1.0