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(); }
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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