How to: Compress Files

Use the System.IO.Compression.GZipStream class to compress and decompress data. You can also use the System.IO.Compression.DeflateStream class, which uses the same compression algorithm; however, compressed GZipStream objects written to a file that has an extension of .gz can be decompressed using many common compression tools.

This example shows how to compress and decompress a directory of files by using the GZipStream class.

Example

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);

                    }
                }
            }
        }

    }
}

See Also

Reference

DeflateStream

GZipStream