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.NET Framework Class Library
GZipStream..::.Flush Method

Flushes the contents of the internal buffer of the current GZipStream object to the underlying stream.

Namespace: System.IO.Compression
Assembly: System (in System.dll)
Syntax
Public Overrides Sub Flush
public override void Flush()
public:
virtual void Flush() override
abstract Flush : unit -> unit 
override Flush : unit -> unit 
Exceptions
ExceptionCondition
ObjectDisposedException

The stream is closed.

Remarks

When writing using the Write method, the data may not be written to the actual stream since writing the data back in chunks can provide better performance. Calling the Flush method forces the data to be written.

Examples

The following code example shows how to use the GZipStream class to compress and decompress a file.


Imports System.IO
Imports System.IO.Compression
Module Module1

    Sub Main()
        ' Path to directory of files to compress.
        Dim dirpath As String = "c:\users\public\reports"

        Dim di As DirectoryInfo = New DirectoryInfo(dirpath)


        ' Compress the directory's files.
        For Each fi As FileInfo In di.GetFiles()
            Compress(fi)
        Next

        ' Decompress all *.gz files in the directory.
        For Each fi As FileInfo In di.GetFiles("*.gz")
            Decompress(fi)
        Next

    End Sub

    ' Method to compress.
    Private Sub Compress(ByVal fi As FileInfo)
        ' Get the stream of the source file.
        Using inFile As FileStream = fi.OpenRead()
            ' Compressing:
            ' Prevent compressing hidden and already compressed files.

            If (File.GetAttributes(fi.FullName) And FileAttributes.Hidden) _
                <> FileAttributes.Hidden And fi.Extension <> ".gz" Then
                ' Create the compressed file.
                Using outFile As FileStream = File.Create(fi.FullName + ".gz")
                    Using Compress As GZipStream = _
                    	New GZipStream(outFile, CompressionMode.Compress)
                    	
                        ' Copy the source file into the compression stream.
                        inFile.CopyTo(Compress)

                        Console.WriteLine("Compressed {0} from {1} to {2} bytes.", _
                                          fi.Name, fi.Length.ToString(), outFile.Length.ToString())

                    End Using
                End Using
            End If
        End Using
    End Sub

    ' Method to decompress.
    Private Sub Decompress(ByVal fi As FileInfo)
        ' Get the stream of the source file.
        Using inFile As FileStream = fi.OpenRead()
            ' Get orignial file extension, for example "doc" from report.doc.gz.
            Dim curFile As String = fi.FullName
            Dim origName = curFile.Remove(curFile.Length - fi.Extension.Length)

            ' Create the decompressed file.
            Using outFile As FileStream = File.Create(origName)
                Using Decompress As GZipStream = New GZipStream(inFile, _
                	CompressionMode.Decompress)
            		
  						' Copy the decompression stream 
                        ' into the output file.
            		    Decompress.CopyTo(outFile)

                    Console.WriteLine("Decompressed: {0}", fi.Name)

                End Using
            End Using
        End Using
    End Sub
End Module


using System;
using System.IO;
using System.IO.Compression;

namespace zip
{

    public class Program
    {

        public static void Main()
        {
            // Path to directory of files to compress and decompress.
            string dirpath = @"c:\users\public\reports";

            DirectoryInfo di = new DirectoryInfo(dirpath);

            // Compress the directory's files.
            foreach (FileInfo fi in di.GetFiles())
            {
                Compress(fi);

            }

            // Decompress all *.gz files in the directory.
            foreach (FileInfo fi in di.GetFiles("*.gz"))
            {
                Decompress(fi);

            }


        }

        public static void Compress(FileInfo fi)
        {
            // Get the stream of the source file.
            using (FileStream inFile = fi.OpenRead())
            {
                // Prevent compressing hidden and 
                // already compressed files.
                if ((File.GetAttributes(fi.FullName) 
                	& FileAttributes.Hidden)
                	!= FileAttributes.Hidden & fi.Extension != ".gz")
                {
                    // Create the compressed file.
                    using (FileStream outFile = 
                    			File.Create(fi.FullName + ".gz"))
                    {
                        using (GZipStream Compress = 
                        	new GZipStream(outFile, 
                        	CompressionMode.Compress))
                        {
                            // Copy the source file into 
                            // the compression stream.
                        inFile.CopyTo(Compress);

                            Console.WriteLine("Compressed {0} from {1} to {2} bytes.",
                                fi.Name, fi.Length.ToString(), outFile.Length.ToString());
                        }
                    }
                }
            }
        }

        public static void Decompress(FileInfo fi)
        {
            // Get the stream of the source file.
            using (FileStream inFile = fi.OpenRead())
            {
                // Get original file extension, for example
                // "doc" from report.doc.gz.
                string curFile = fi.FullName;
                string origName = curFile.Remove(curFile.Length - 
                		fi.Extension.Length);

                //Create the decompressed file.
                using (FileStream outFile = File.Create(origName))
                {
                    using (GZipStream Decompress = new GZipStream(inFile,
                            CompressionMode.Decompress))
                    {
                        // Copy the decompression stream 
                        // into the output file.
            		    Decompress.CopyTo(outFile);
            		    
                        Console.WriteLine("Decompressed: {0}", fi.Name);

                    }
                }
            }
        }

    }
}

Version Information

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
Platforms

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.