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BinaryReader.ReadDouble Method

Reads an 8-byte floating point value from the current stream and advances the current position of the stream by eight bytes.

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

'Declaration
Public Overridable Function ReadDouble As Double
'Usage
Dim instance As BinaryReader 
Dim returnValue As Double 

returnValue = instance.ReadDouble()

Return Value

Type: System.Double
An 8-byte floating point value read from the current stream.

ExceptionCondition
EndOfStreamException

The end of the stream is reached.

ObjectDisposedException

The stream is closed.

IOException

An I/O error occurs.

BinaryReader does not restore the file position after an unsuccessful read.

BinaryReader reads this data type in little-endian format.

For a list of common I/O tasks, see Common I/O Tasks.

The following code example shows how to read and write Double data to memory by using the BinaryReader and BinaryWriter classes on top of the MemoryStream class. MemoryStream only reads and writes Byte data.

Imports System
Imports System.IO

Public Class BinaryRW

    Shared Sub Main()

        Dim i As Integer 
        Const upperBound As Integer = 1000

        ' Create random data to write to the stream. 
        Dim dataArray(upperBound) As Double 
        Dim randomGenerator As New Random()
        For i = 0 To upperBound
            dataArray(i) = 100.1 * randomGenerator.NextDouble()
        Next i

        Dim binWriter As New BinaryWriter(New MemoryStream())
        Try 

            ' Write data to the stream.
            Console.WriteLine("Writing data to the stream.")

            For i = 0 To upperBound
                binWriter.Write(dataArray(i))
            Next i

            ' Create a reader using the stream from the writer. 
            Dim binReader As New BinaryReader(binWriter.BaseStream)

            ' Return to the beginning of the stream.
            binReader.BaseStream.Position = 0

            ' Read and verify the data. 
            Try
                Console.WriteLine("Verifying the written data.")
                For i = 0 To upperBound
                    If binReader.ReadDouble() <> dataArray(i) Then
                        Console.WriteLine("Error writing data.")
                        Exit For 
                    End If 
                Next i
                Console.WriteLine("The data was written and verified.")
            Catch ex As EndOfStreamException
                Console.WriteLine("Error writing data: {0}.", _
                    ex.GetType().Name)
            End Try 
        Finally
            binWriter.Close()
        End Try 

    End Sub 
End Class

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

.NET Framework

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

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

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