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BinaryWriter.Write Method (Byte(), Int32, Int32)

Writes a region of a byte array to the current stream.

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

Public Overridable Sub Write ( _
	buffer As Byte(), _
	index As Integer, _
	count As Integer _


Type: System.Byte()

A byte array containing the data to write.

Type: System.Int32

The starting point in buffer at which to begin writing.

Type: System.Int32

The number of bytes to write.


The buffer length minus index is less than count.


buffer is Nothing.


index or count is negative.


An I/O error occurs.


The stream is closed.

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

The following code example shows how to write binary data using memory as a backing store, and then verify that the data was written correctly.

Imports System.IO

Module Module1

    Sub Main()
        Const upperBound As Integer = 1000
        Dim dataArray(upperBound) As Byte 
        Dim verifyArray(upperBound) As Byte 

        Dim randomGenerator As New Random

        Using binWriter As New BinaryWriter(New MemoryStream())
            Console.WriteLine("Writing the data.")
            binWriter.Write(dataArray, 0, dataArray.Length)

            Using binReader As New BinaryReader(binWriter.BaseStream)
                binReader.BaseStream.Position = 0

                If binReader.Read(verifyArray, 0, dataArray.Length) <> dataArray.Length Then
                    Console.WriteLine("Error writing the data.")
                End If 
            End Using 
        End Using 

        For i As Integer = 0 To upperBound
            If verifyArray(i) <> dataArray(i) Then
                Console.WriteLine("Error writing the data.")
            End If 
        Next i

        Console.WriteLine("The data was written and verified.")
    End Sub 

End Module

.NET Framework

Supported in: 4.5, 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

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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