How to: Compress and Extract Files

How to: Compress and Extract Files

 

The System.IO.Compression namespace contains the following types for compressing and decompressing files and streams. You can also use these types to read and modify the contents of a compressed file:

The following examples show some of the functions you can perform when working with compressed files.

Example

This example shows how to create and extract a compressed file that has a .zip file name extension by using the ZipFile class. It compresses the contents of a folder into a new .zip file and then extracts that content to a new folder. To use the ZipFile class, you must reference the System.IO.Compression.FileSystem assembly in your project.

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

namespace ConsoleApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            string startPath = @"c:\example\start";
            string zipPath = @"c:\example\result.zip";
            string extractPath = @"c:\example\extract";

            ZipFile.CreateFromDirectory(startPath, zipPath);

            ZipFile.ExtractToDirectory(zipPath, extractPath);
        }
    }
}

Example

The next example shows how to iterate through the contents of an existing .zip file and extract files that have a .txt extension. It uses the ZipArchive class to access an existing .zip file, and the ZipArchiveEntry class to inspect the individual entries in the compressed file. It uses an extension method (ExtractToFile) for the ZipArchiveEntry object. The extension method is available in the System.IO.Compression.ZipFileExtensions class. To use the ZipFileExtensions class, you must reference the System.IO.Compression.FileSystem assembly in your project.

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string zipPath = @"c:\example\start.zip";
            string extractPath = @"c:\example\extract";

            using (ZipArchive archive = ZipFile.OpenRead(zipPath))
            {
                foreach (ZipArchiveEntry entry in archive.Entries)
                {
                    if (entry.FullName.EndsWith(".txt", StringComparison.OrdinalIgnoreCase))
                    {
                        entry.ExtractToFile(Path.Combine(extractPath, entry.FullName));
                    }
                }
            } 
        }
    }
}

Example

The next example uses the ZipArchive class to access an existing .zip file, and adds a new file to the compressed file. The new file gets compressed when you add it to the existing .zip file.

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

namespace ConsoleApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            using (FileStream zipToOpen = new FileStream(@"c:\users\exampleuser\release.zip", FileMode.Open))
            {
                using (ZipArchive archive = new ZipArchive(zipToOpen, ZipArchiveMode.Update))
                {
                    ZipArchiveEntry readmeEntry = archive.CreateEntry("Readme.txt");
                    using (StreamWriter writer = new StreamWriter(readmeEntry.Open()))
                    {
                            writer.WriteLine("Information about this package.");
                            writer.WriteLine("========================");
                    }
                }
            }
        }
    }
}

Example

You can also use the GZipStream and DeflateStream classes to compress and decompress data. They use the same compression algorithm. Compressed GZipStream objects that are written to a file that has an extension of .gz can be decompressed by using many common tools in addition to the methods provided by GZipStream. This example shows how to compress and decompress a directory of files by using the GZipStream class.

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

namespace zip
{
    public class Program
    {
        private static string directoryPath = @"c:\temp";
        public static void Main()
        {
            DirectoryInfo directorySelected = new DirectoryInfo(directoryPath);
            Compress(directorySelected);

            foreach (FileInfo fileToDecompress in directorySelected.GetFiles("*.gz"))
            {
                Decompress(fileToDecompress);
            }
        }

        public static void Compress(DirectoryInfo directorySelected)
        {
            foreach (FileInfo fileToCompress in directorySelected.GetFiles())
            {
                using (FileStream originalFileStream = fileToCompress.OpenRead())
                {
                    if ((File.GetAttributes(fileToCompress.FullName) & 
                       FileAttributes.Hidden) != FileAttributes.Hidden & fileToCompress.Extension != ".gz")
                    {
                        using (FileStream compressedFileStream = File.Create(fileToCompress.FullName + ".gz"))
                        {
                            using (GZipStream compressionStream = new GZipStream(compressedFileStream, 
                               CompressionMode.Compress))
                            {
                                originalFileStream.CopyTo(compressionStream);

                            }
                        }
                        FileInfo info = new FileInfo(directoryPath + "\\" + fileToCompress.Name + ".gz");
                        Console.WriteLine("Compressed {0} from {1} to {2} bytes.",
                        fileToCompress.Name, fileToCompress.Length.ToString(), info.Length.ToString());
                    }

                }
            }
        }

        public static void Decompress(FileInfo fileToDecompress)
        {
            using (FileStream originalFileStream = fileToDecompress.OpenRead())
            {
                string currentFileName = fileToDecompress.FullName;
                string newFileName = currentFileName.Remove(currentFileName.Length - fileToDecompress.Extension.Length);

                using (FileStream decompressedFileStream = File.Create(newFileName))
                {
                    using (GZipStream decompressionStream = new GZipStream(originalFileStream, CompressionMode.Decompress))
                    {
                        decompressionStream.CopyTo(decompressedFileStream);
                        Console.WriteLine("Decompressed: {0}", fileToDecompress.Name);
                    }
                }
            }
        }
    }
}
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