ToDouble Method

BitConverter.ToDouble Method (Byte(), Int32)

 

Returns a double-precision floating point number converted from eight bytes at a specified position in a byte array.

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

Public Shared Function ToDouble (
	value As Byte(),
	startIndex As Integer
) As Double

Parameters

value
Type: System.Byte()

An array of bytes.

startIndex
Type: System.Int32

The starting position within value.

Return Value

Type: System.Double

A double precision floating point number formed by eight bytes beginning at startIndex.

Exception Condition
ArgumentException

startIndex is greater than or equal to the length of value minus 7, and is less than or equal to the length of value minus 1.

ArgumentNullException

value is null.

ArgumentOutOfRangeException

startIndex is less than zero or greater than the length of value minus 1.

The ToDouble method converts the bytes from index startIndex to startIndex + 7 to a Double value. The order of bytes in the array must reflect the endianness of the computer system's architecture; for more information, see the Remarks section of the BitConverter class topic.

The following code example converts elements of Byte arrays to Double values with the ToDouble method.

' Example of the BitConverter.ToDouble method.
Imports System
Imports Microsoft.VisualBasic

Module BytesToDoubleDemo

    Const formatter As String = "{0,5}{1,27}{2,27:E16}"

    ' Convert eight Byte array elements to a Double and display it.
    Sub BAToDouble( bytes( ) As Byte, index As Integer )

        Dim value As Double = BitConverter.ToDouble( bytes, index )

        Console.WriteLine( formatter, index, _
            BitConverter.ToString( bytes, index, 8 ), value )
    End Sub 

    ' Display a Byte array, using multiple lines if necessary.
    Sub WriteMultiLineByteArray( bytes( ) As Byte )

        Const rowSize As Integer = 20 
        Dim iter As Integer

        Console.WriteLine( "initial Byte array" )
        Console.WriteLine( "------------------" )

        For iter = 0 To bytes.Length - rowSize - 1 Step rowSize
            Console.Write( _
                BitConverter.ToString( bytes, iter, rowSize ) )
            Console.WriteLine( "-" )
        Next iter

        Console.WriteLine( BitConverter.ToString( bytes, iter ) )
        Console.WriteLine( )
    End Sub

    Sub Main( )
        Dim byteArray as Byte( ) = { _
              0,   0,   0,   0,   0,   0,   0,   0, 240,  63, _
              0,   0,   0,   0,   0, 224, 111,  64,   0,   0, _
            224, 255, 255, 255, 239,  65,   0,   0,   0,   0, _
              0,   0, 112,  63,   0,   0,   0,   0,   0,   0, _
            240,  61, 223, 136,  30,  28, 254, 116, 170,   1, _
            250,  89, 140,  66, 202, 192, 243,  63, 251,  89, _
            140,  66, 202, 192, 243,  63, 252,  89, 140,  66, _
            202, 192, 243,  63,  82, 211, 187, 188, 232, 126, _
             61, 126, 255, 255, 255, 255, 255, 255, 239, 255, _
            255, 255, 255, 255, 255, 239, 127,   1,   0,   0, _
              0,   0,   0,   0,   0, 248, 255,   0,   0,   0, _
              0,   0,   0, 240, 255,   0,   0,   0,   0,   0, _
              0, 240, 127 }

        Console.WriteLine( _
            "This example of the BitConverter.ToDouble( Byte( ), " & _
            "Integer ) " & vbCrLf & "method generates the " & _
            "following output. It converts elements " & vbCrLf & _
            "of a Byte array to Double values." & vbCrLf )

        WriteMultiLineByteArray( byteArray )

        Console.WriteLine( formatter, "index", "array elements", _
            "Double" )
        Console.WriteLine( formatter, "-----", "--------------", _
            "------" )

        ' Convert Byte array elements to Double values.
        BAToDouble( byteArray, 0 )
        BAToDouble( byteArray, 2 )
        BAToDouble( byteArray, 10 )
        BAToDouble( byteArray, 18 )
        BAToDouble( byteArray, 26 )
        BAToDouble( byteArray, 34 )
        BAToDouble( byteArray, 42 )
        BAToDouble( byteArray, 50 )
        BAToDouble( byteArray, 58 )
        BAToDouble( byteArray, 66 )
        BAToDouble( byteArray, 74 )
        BAToDouble( byteArray, 82 )
        BAToDouble( byteArray, 89 )
        BAToDouble( byteArray, 97 )
        BAToDouble( byteArray, 99 )
        BAToDouble( byteArray, 107 )
        BAToDouble( byteArray, 115 )
    End Sub 
End Module

' This example of the BitConverter.ToDouble( Byte( ), Integer )
' method generates the following output. It converts elements
' of a Byte array to Double values.
' 
' initial Byte array
' ------------------
' 00-00-00-00-00-00-00-00-F0-3F-00-00-00-00-00-E0-6F-40-00-00-
' E0-FF-FF-FF-EF-41-00-00-00-00-00-00-70-3F-00-00-00-00-00-00-
' F0-3D-DF-88-1E-1C-FE-74-AA-01-FA-59-8C-42-CA-C0-F3-3F-FB-59-
' 8C-42-CA-C0-F3-3F-FC-59-8C-42-CA-C0-F3-3F-52-D3-BB-BC-E8-7E-
' 3D-7E-FF-FF-FF-FF-FF-FF-EF-FF-FF-FF-FF-FF-FF-EF-7F-01-00-00-
' 00-00-00-00-00-F8-FF-00-00-00-00-00-00-F0-FF-00-00-00-00-00-
' 00-F0-7F
' 
' index             array elements                     Double
' -----             --------------                     ------
'     0    00-00-00-00-00-00-00-00    0.0000000000000000E+000
'     2    00-00-00-00-00-00-F0-3F    1.0000000000000000E+000
'    10    00-00-00-00-00-E0-6F-40    2.5500000000000000E+002
'    18    00-00-E0-FF-FF-FF-EF-41    4.2949672950000000E+009
'    26    00-00-00-00-00-00-70-3F    3.9062500000000000E-003
'    34    00-00-00-00-00-00-F0-3D    2.3283064365386963E-010
'    42    DF-88-1E-1C-FE-74-AA-01    1.2345678901234500E-300
'    50    FA-59-8C-42-CA-C0-F3-3F    1.2345678901234565E+000
'    58    FB-59-8C-42-CA-C0-F3-3F    1.2345678901234567E+000
'    66    FC-59-8C-42-CA-C0-F3-3F    1.2345678901234569E+000
'    74    52-D3-BB-BC-E8-7E-3D-7E    1.2345678901234569E+300
'    82    FF-FF-FF-FF-FF-FF-EF-FF   -1.7976931348623157E+308
'    89    FF-FF-FF-FF-FF-FF-EF-7F    1.7976931348623157E+308
'    97    01-00-00-00-00-00-00-00    4.9406564584124654E-324
'    99    00-00-00-00-00-00-F8-FF                        NaN
'   107    00-00-00-00-00-00-F0-FF                  -Infinity
'   115    00-00-00-00-00-00-F0-7F                   Infinity

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
Return to top
Show:
© 2016 Microsoft