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BinaryWriter Class

Writes primitive types in binary to a stream and supports writing strings in a specific encoding.

For a list of all members of this type, see BinaryWriter Members.

System.Object
   System.IO.BinaryWriter

[Visual Basic]
<Serializable>
Public Class BinaryWriter
   Implements IDisposable
[C#]
[Serializable]
public class BinaryWriter : IDisposable
[C++]
[Serializable]
public __gc class BinaryWriter : public IDisposable
[JScript]
public
   Serializable
class BinaryWriter implements IDisposable

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Remarks

A derived class can override the methods of this class to give unique character encodings.

The following table lists examples of other typical or related I/O tasks.

To do this... See the example in this topic...
Create a text file. Writing Text to a File
Write to a text file. Writing Text to a File
Read from a text file. Reading Text from a File
Read from a binary file. Reading and Writing to a Newly Created Data File
Write to a binary file. Reading and Writing to a Newly Created Data File

Example

[Visual Basic, C#, C++] The following code example demonstrates how to store and retrieve application settings in a file.

[Visual Basic] 
Imports Microsoft.VisualBasic
Imports System
Imports System.IO
Imports System.Security.Permissions

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

' 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.
                If binReader.PeekChar() <> -1 Then
                    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

[C#] 
using System;
using System.IO;
using System.Security.Permissions;

class Test
{
    static void Main()
    {
        // Load application settings.
        AppSettings appSettings = new AppSettings();
        Console.WriteLine("App settings.\nAspect Ratio: {0}, " +
            "Lookup directory: {1},\nAuto save time: {2} minutes, " +
            "Show status bar: {3}\n", 
            new Object[4]{appSettings.AspectRatio.ToString(), 
            appSettings.LookupDir, appSettings.AutoSaveTime.ToString(),
            appSettings.ShowStatusBar.ToString()});

        // Change the settings.
        appSettings.AspectRatio   = 1.250F;
        appSettings.LookupDir     = @"C:\Temp";
        appSettings.AutoSaveTime  = 10;
        appSettings.ShowStatusBar = true;

        // Save the new settings.
        appSettings.Close();
    }
}

// Store and retrieve application settings.
class AppSettings
{
    const string fileName = "AppSettings#@@#.dat";
    float  aspectRatio;
    string lookupDir;
    int    autoSaveTime;
    bool   showStatusBar;

    public float AspectRatio
    {
        get{ return aspectRatio; }
        set{ aspectRatio = value; }
    }

    public string LookupDir
    {
        get{ return lookupDir; }
        set{ lookupDir = value; }
    }

    public int AutoSaveTime
    {
        get{ return autoSaveTime; }
        set{ autoSaveTime = value; }
    }

    public bool ShowStatusBar
    {
        get{ return showStatusBar; }
        set{ showStatusBar = value; }
    }

    public AppSettings()
    {
        // Create default application settings.
        aspectRatio   = 1.3333F;
        lookupDir     = @"C:\AppDirectory";
        autoSaveTime  = 30;
        showStatusBar = false;

        if(File.Exists(fileName))
        {
            BinaryReader binReader = 
                new BinaryReader(File.Open(fileName, FileMode.Open));
            try
            {
                // If the file is not empty, 
                // read the application settings.
                if(binReader.PeekChar() != -1)
                {
                    aspectRatio   = binReader.ReadSingle();
                    lookupDir     = binReader.ReadString();
                    autoSaveTime  = binReader.ReadInt32();
                    showStatusBar = binReader.ReadBoolean();
                }
            }

            // 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(EndOfStreamException e)
            {
                Console.WriteLine("{0} caught and ignored. " + 
                    "Using default values.", e.GetType().Name);
            }
            finally
            {
                binReader.Close();
            }
        }

    }

    // Create a file and store the application settings.
    public void Close()
    {
        using(BinaryWriter binWriter = 
            new BinaryWriter(File.Open(fileName, FileMode.Create)))
        {
            binWriter.Write(aspectRatio);
            binWriter.Write(lookupDir);
            binWriter.Write(autoSaveTime);
            binWriter.Write(showStatusBar);
        }
    }
}

[C++] 
#using <mscorlib.dll>
using namespace System;
using namespace System::IO;
using namespace System::Security::Permissions;

// Store and retrieve application settings.
__gc class AppSettings
{
    static String* fileName = "AppSettings#@@#.dat";
    float   aspectRatio;
    String* lookupDir;
    int     autoSaveTime;
    Boolean showStatusBar;

public:
    __property float get_AspectRatio()
    { return aspectRatio; }
    __property void set_AspectRatio(float value)
    { aspectRatio = value; }

    __property String* get_LookupDir()
    { return lookupDir; }
    __property void set_LookupDir(String* value)
    { lookupDir = value; }

    __property int get_AutoSaveTime()
     { return autoSaveTime; }
    __property void set_AutoSaveTime(int value)
    { autoSaveTime = value; }

    __property Boolean get_ShowStatusBar()
    { return showStatusBar; }
    __property void set_ShowStatusBar(Boolean value)
    { showStatusBar = value; }

    AppSettings()
    {
        // Create default application settings.
        aspectRatio   = 1.3333F;
        lookupDir     = "C:\\AppDirectory";
        autoSaveTime  = 30;
        showStatusBar = false;

        if(File::Exists(fileName))
        {
            BinaryReader* binReader = 
                new BinaryReader(File::Open(fileName, FileMode::Open));
            try
            {
                // If the file is not empty, 
                // read the application settings.
                if(binReader->PeekChar() != -1)
                {
                    aspectRatio   = binReader->ReadSingle();
                    lookupDir     = binReader->ReadString();
                    autoSaveTime  = binReader->ReadInt32();
                    showStatusBar = binReader->ReadBoolean();
                    return;
                }
            }

            // 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(EndOfStreamException* e)
            {
                Console::WriteLine(S"{0} caught and ignored. "
                    S"Using default values.", e->GetType()->Name);
            }
            __finally
            {
                binReader->Close();
            }
        }
    }

    // Create a file and store the application settings.
    void Close()
    {
        BinaryWriter* binWriter = 
            new BinaryWriter(File::Open(fileName, FileMode::Create));
        try
        {
            binWriter->Write(aspectRatio);
            binWriter->Write(lookupDir);
            binWriter->Write(autoSaveTime);
            binWriter->Write(showStatusBar);
        }
        __finally
        {
            binWriter->Close();
        }
    }
};

void main()
{
    // Load application settings.
    AppSettings* appSettings = new AppSettings();
    Object* someObject[] = {appSettings->AspectRatio.ToString(), 
        appSettings->LookupDir, appSettings->AutoSaveTime.ToString(), 
        appSettings->ShowStatusBar.ToString()};
    Console::WriteLine(S"App settings.\nAspect Ratio: {0}, " 
        S"Lookup directory: {1},\nAuto save time: {2} minutes, " 
        S"Show status bar: {3}\n", someObject);

    // Change the settings.
    appSettings->AspectRatio   = 1.250F;
    appSettings->LookupDir     = "C:\\Temp";
    appSettings->AutoSaveTime  = 10;
    appSettings->ShowStatusBar = true;

    // Save the new settings.
    appSettings->Close();
}

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Namespace: System.IO

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework

Assembly: Mscorlib (in Mscorlib.dll)

See Also

BinaryWriter Members | System.IO Namespace | Encoding | Working with I/O | Reading Text from a File | Writing Text to a File | Basic File I/O | Reading and Writing to a Newly Created Data File

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