FileStream.Flush Method

Definition

Namespace:

System.IO

Assembly:

System.Runtime.dll

Clears buffers for this stream and causes any buffered data to be written to the file.

Overloads

Flush()	Clears buffers for this stream and causes any buffered data to be written to the file.
Flush(Boolean)	Clears buffers for this stream and causes any buffered data to be written to the file, and also clears all intermediate file buffers.

Flush()

Source:

FileStream.cs

Clears buffers for this stream and causes any buffered data to be written to the file.

public:
 override void Flush();

public override void Flush ();

override this.Flush : unit -> unit

Public Overrides Sub Flush ()

Exceptions

IOException

An I/O error occurred.

ObjectDisposedException

The stream is closed.

Examples

This code example is part of a larger example provided for the Lock method.

// Update the file.
case 'W':
   try
   {
      fileStream->Seek( textLength, SeekOrigin::Begin );
      fileStream->Read( readText, textLength - 1, byteCount );
      tempString = gcnew String( uniEncoding->GetChars( readText, textLength - 1, byteCount ) );
      recordNumber = Int32::Parse( tempString ) + 1;
      fileStream->Seek( textLength, SeekOrigin::Begin );
      fileStream->Write( uniEncoding->GetBytes( recordNumber.ToString() ), 0, byteCount );
      fileStream->Flush();
      Console::WriteLine( "Record has been updated." );
   }

// Update the file.
case 'W':
    try
    {
        fileStream.Seek(textLength,
            SeekOrigin.Begin);
        fileStream.Read(
            readText, textLength - 1, byteCount);
        tempString = new String(
            uniEncoding.GetChars(
            readText, textLength - 1, byteCount));
        recordNumber = int.Parse(tempString) + 1;
        fileStream.Seek(
            textLength, SeekOrigin.Begin);
        fileStream.Write(uniEncoding.GetBytes(
            recordNumber.ToString()),
            0, byteCount);
        fileStream.Flush();
        Console.WriteLine(
            "Record has been updated.");
    }

| 'W' ->
    // Update the file.
    try

        fileStream.Seek(textLength, SeekOrigin.Begin) |> ignore
        fileStream.Read(readText, textLength - 1, byteCount) |> ignore
        tempString <- String(uniEncoding.GetChars readText, textLength - 1, byteCount)
        recordNumber <- Int32.Parse tempString + 1
        fileStream.Seek(textLength, SeekOrigin.Begin) |> ignore
        fileStream.Write(string recordNumber |> uniEncoding.GetBytes, 0, byteCount)
        fileStream.Flush()
        printfn "Record has been updated."

' Update the file.
Case "W"C
    Try
        aFileStream.Seek(textLength, _
            SeekOrigin.Begin)
        aFileStream.Read( _
            readText, textLength - 1, byteCount)
        tempString = New String( _
            uniEncoding.GetChars( _
            readText, textLength - 1, byteCount))
        recordNumber = _
            Integer.Parse(tempString) + 1
        aFileStream.Seek( _
            textLength, SeekOrigin.Begin)
        aFileStream.Write(uniEncoding.GetBytes( _
            recordNumber.ToString()), 0, byteCount)
        aFileStream.Flush()
        Console.WriteLine( _
            "Record has been updated.")

Remarks

This method overrides Stream.Flush.

When you call the FileStream.Flush method, the operating system I/O buffer is also flushed.

A stream's encoder is not flushed unless you explicitly call Flush or dispose of the object. Setting StreamWriter.AutoFlush to true means that data will be flushed from the buffer to the stream, but the encoder state will not be flushed. This allows the encoder to keep its state (partial characters) so that it can encode the next block of characters correctly. This scenario affects UTF8 and UTF7 where certain characters can only be encoded after the encoder receives the adjacent character or characters.

Because a buffer can be used for either reading or writing, Flush() performs the following two functions:

• Any data previously written to the buffer is copied to the file and the buffer is cleared except for its encoder state.

• If BufferedStream.CanSeek is true and data was previously copied from the file to the buffer for reading, the current position within the file is decremented by the number of unread bytes in the buffer. The buffer is then cleared.

Use the Flush(Boolean) method overload when you want to ensure that all buffered data in intermediate file buffers is written to disk.

See also

• Flush(Boolean)
• How to: Write Text to a File

Flush(Boolean)

Source:

FileStream.cs

Clears buffers for this stream and causes any buffered data to be written to the file, and also clears all intermediate file buffers.

public:
 virtual void Flush(bool flushToDisk);

public virtual void Flush (bool flushToDisk);

override this.Flush : bool -> unit

Public Overridable Sub Flush (flushToDisk As Boolean)

Parameters

flushToDisk

Boolean

true to flush all intermediate file buffers; otherwise, false.

Remarks

Use this overload when you want to ensure that all buffered data in intermediate file buffers is written to disk.

When you call the Flush method, the operating system I/O buffer is also flushed.

See also

• Flush()