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BinaryWriter Class

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

Namespace:  System.IO
Assembly:  mscorlib (in mscorlib.dll)
[SerializableAttribute]
[ComVisibleAttribute(true)]
public ref class BinaryWriter : IDisposable

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

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.

using namespace System;
using namespace System::IO;
using namespace System::Security::Permissions;

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

public:

   property float AspectRatio
   {
      float get()
      {
         return aspectRatio;
      }

      void set( float value )
      {
         aspectRatio = value;
      }

   }

   property String^ LookupDir
   {
      String^ get()
      {
         return lookupDir;
      }

      void set( String^ value )
      {
         lookupDir = value;
      }

   }

   property int AutoSaveTime
   {
      int get()
      {
         return autoSaveTime;
      }

      void set( int value )
      {
         autoSaveTime = value;
      }

   }

   property Boolean ShowStatusBar
   {
      Boolean get()
      {
         return showStatusBar;
      }

      void set( 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 = gcnew 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. 
            array<Byte>^testArray = gcnew array<Byte>(3);
            int count = binReader->Read(testArray, 0, 3);
            if ( count != -1 )
            {

               // Reset the position in the stream to zero.
               binReader->BaseStream->Seek(0, SeekOrigin::Begin);

               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( "{0} caught and ignored. " 
            "Using default values.", e->GetType()->Name );
         }
         finally
         {
            binReader->Close();
         }


      }
   }


   // Create a file and store the application settings. 
   void Close()
   {

      BinaryWriter^ binWriter = gcnew BinaryWriter( File::Open( fileName, FileMode::Create ) );
      try
      {
         binWriter->Write( aspectRatio );
         binWriter->Write( lookupDir );
         binWriter->Write( autoSaveTime );
         binWriter->Write( showStatusBar );
      }
      finally
      {
         binWriter->Close();
      }


   }

};

int main()
{

   // Load application settings.
   AppSettings^ appSettings = gcnew AppSettings;
   array<Object^>^someObject = {appSettings->AspectRatio.ToString(),appSettings->LookupDir,appSettings->AutoSaveTime.ToString(),appSettings->ShowStatusBar.ToString()};
   Console::WriteLine( "App settings:\nAspect Ratio: {0}, " 
   "Lookup directory: {1},\nAuto save time: {2} minutes, " 
   "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();
}
System::Object
  System.IO::BinaryWriter
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

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