Decimal Narrowing Conversion (Decimal to Double)

Converts a Decimal to a double-precision floating-point number.

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

Public Shared Narrowing Operator CType ( _
	value As Decimal _
) As Double


Type: System.Decimal
A Decimal to convert.

Return Value

Type: System.Double
A double-precision floating-point number that represents the converted Decimal.

This operation can produce round-off errors because a double-precision floating-point number has fewer significant digits than a Decimal.

This operator supports the explicit conversion of a Decimal to a Double. The syntax for such explicit conversions is language-dependent, and individual language compilers can provide different implementations and return different results. The example illustrates the different return values when you explicitly convert a Decimal value to a Double value by using C# and Visual Basic. To perform a conversion that is independent of language, you can call the ToDouble or the Convert.ToDouble(Decimal) method.

The following code example converts Decimal numbers to Double values using the explicit Decimal to Double conversion.

' Example of the explicit conversions from decimal to float and 
' decimal to double.
Module Example

   Const formatter As String = "{0,30}{1,17}{2,23}"

   ' Convert the Decimal argument to a floating point value
   ' No exceptions are thrown.
   Public Sub DecimalToSgl_Dbl(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal argument As Decimal)
      Dim SingleValue As Single
      Dim DoubleValue As Double

      ' Convert the argument to a Single value.
      SingleValue = CSng(argument)

      ' Convert the argument to a Double value.
      DoubleValue = CDbl(argument)

      outputBlock.Text += String.Format(formatter, argument, _
          SingleValue, DoubleValue) + vbCrLf
   End Sub

   Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
      outputBlock.Text += String.Format(formatter, "Decimal argument", _
          "Single", "Double") + vbCrLf
      outputBlock.Text += String.Format(formatter, "----------------", _
          "-----", "------") + vbCrLf

      ' Convert decimal values and display the results.
      DecimalToSgl_Dbl(outputBlock, 0.0000000000000000000000000001D)
      DecimalToSgl_Dbl(outputBlock, 0.0000000000123456789123456789D)
      DecimalToSgl_Dbl(outputBlock, 123D)
      DecimalToSgl_Dbl(outputBlock, New Decimal(123000000, 0, 0, False, 6))
      DecimalToSgl_Dbl(outputBlock, 123456789.123456789D)
      DecimalToSgl_Dbl(outputBlock, 123456789123456789123456789D)
      DecimalToSgl_Dbl(outputBlock, Decimal.MinValue)
      DecimalToSgl_Dbl(outputBlock, Decimal.MaxValue)
   End Sub
End Module
' The example displays the following output:
'                  Decimal argument           Single                 Double
'                  ----------------            -----                 ------
'    0.0000000000000000000000000001            1E-28                  1E-28
'    0.0000000000123456789123456789     1.234568E-11   1.23456789123457E-11
'                               123              123                    123
'                        123.000000              123                    123
'               123456789.123456789     1.234568E+08       123456789.123457
'       123456789123456789123456789     1.234568E+26   1.23456789123457E+26
'    -79228162514264337593543950335    -7.922816E+28  -7.92281625142643E+28
'     79228162514264337593543950335     7.922816E+28   7.92281625142643E+28


Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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