FileStream.WriteByte Method (Byte)

 

Writes a byte to the current position in the file stream.

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

Public Overrides Sub WriteByte (
	value As Byte
)

Parameters

value
Type: System.Byte

A byte to write to the stream.

Exception Condition
ObjectDisposedException

The stream is closed.

NotSupportedException

The stream does not support writing.

This method overrides WriteByte.

Use WriteByte to write a byte to a FileStream efficiently. If the stream is closed or not writable, an exception will be thrown.

System_CAPS_noteNote

Use the CanWrite property to determine whether the current instance supports writing. For additional information, see CanWrite.

Notes to Implementers:

The default implementation on Stream creates a new single-byte array and then calls Write. While this is formally correct, it is inefficient. Any stream with an internal buffer should override this method and provide a much more efficient version that reads the buffer directly, avoiding the extra array allocation on every call.

For a list of common file and directory operations, see Common I-O Tasks.

The following code example shows how to write data to a file, byte by byte, and then verify that the data was written correctly.

Imports Microsoft.VisualBasic
Imports System
Imports System.IO
Imports System.Text

Class FStream

    Shared Sub Main()

        Const fileName As String = "Test#@@#.dat"

        ' Create random data to write to the file.
        Dim dataArray(100000) As Byte
        Dim randomGenerator As New Random()
        randomGenerator.NextBytes(dataArray)

        Dim fileStream As FileStream = _
            new FileStream(fileName, FileMode.Create)
        Try

            ' Write the data to the file, byte by byte.
            For i As Integer = 0 To dataArray.Length - 1
                fileStream.WriteByte(dataArray(i))
            Next i

            ' Set the stream position to the beginning of the stream.
            fileStream.Seek(0, SeekOrigin.Begin)

            ' Read and verify the data.
            For i As Integer = 0 To _
                CType(fileStream.Length, Integer) - 1

                If dataArray(i) <> fileStream.ReadByte() Then
                    Console.WriteLine("Error writing data.")
                    Return
                End If
            Next i
            Console.WriteLine("The data was written to {0} " & _
                "and verified.", fileStream.Name)
        Finally
            fileStream.Close()
        End Try

    End Sub
End Class

Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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