BinaryReader Class
Reads primitive data types as binary values in a specific encoding.
Assembly: mscorlib (in mscorlib.dll)
For a list of common I/O tasks, see Common I/O Tasks.
The following code example demonstrates how to store and retrieve application settings in a file.
Imports Microsoft.VisualBasic Imports System Imports System.IO Imports System.Security.Permissions ' Store and retrieve application settings. Public Class AppSettings Const fileName As String = "AppSettings#@@#.dat" Dim aspRatio As Single Dim lkupDir As String Dim saveTime As Integer Dim statusBar As Boolean Property AspectRatio As Single Get Return aspRatio End Get Set aspRatio = Value End Set End Property Property LookupDir As String Get Return lkupDir End Get Set lkupDir = Value End Set End Property Property AutoSaveTime As Integer Get Return saveTime End Get Set saveTime = Value End Set End Property Property ShowStatusBar As Boolean Get Return statusBar End Get Set statusBar = Value End Set End Property Sub New() ' Create default application settings. aspRatio = 1.3333 lkupDir = "C:\AppDirectory" saveTime = 30 statusBar = False If File.Exists(fileName) Then Dim binReader As New BinaryReader( _ File.Open(fileName, FileMode.Open)) Try ' If the file is not empty, ' read the application settings. ' First read 4 bytes into a buffer to ' determine if the file is empty. Dim testArray As Byte() = {0,0,0,0} Dim count As Integer = binReader.Read(testArray, 0, 3) If count <> 0 Then ' Reset the position in the stream to zero. binReader.BaseStream.Seek(0, SeekOrigin.Begin) aspRatio = binReader.ReadSingle() lkupDir = binReader.ReadString() saveTime = binReader.ReadInt32() statusBar = binReader.ReadBoolean() Return End If ' If the end of the stream is reached before reading ' the four data values, ignore the error and use the ' default settings for the remaining values. Catch ex As EndOfStreamException Console.WriteLine("{0} caught and ignored. " & _ "Using default values.", ex.GetType().Name) Finally binReader.Close() End Try End If End Sub ' Create a file and store the application settings. Sub Close() Dim binWriter As New BinaryWriter( _ File.Open(fileName, FileMode.Create)) Try binWriter.Write(aspRatio) binWriter.Write(lkupDir) binWriter.Write(saveTime) binWriter.Write(statusBar) Finally binWriter.Close() End Try End Sub End Class Public Class Test Shared Sub Main() ' Load application settings. Dim appSettings As New AppSettings() Console.WriteLine("App settings:" & vbcrLf & "Aspect " & _ "Ratio: {0}, Lookup directory: {1}," & vbcrLf & "Auto " & _ "save time: {2} minutes, Show status bar: {3}" & vbCrLf, _ New Object(3){appSettings.AspectRatio.ToString(), _ appSettings.LookupDir, _ appSettings.AutoSaveTime.ToString(), _ appSettings.ShowStatusBar.ToString()}) ' Change the settings. appSettings.AspectRatio = 1.250 appSettings.LookupDir = "C:\Temp" appSettings.AutoSaveTime = 10 appSettings.ShowStatusBar = True ' Save the new settings. appSettings.Close() 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.