Compress a single file using C#

Question

I am using .NET 4.5, and the ZipFile class works great if I am trying to zip up an entire directory with "CreateFromDirectory". However, I only want to zip up one file in the directory. I tried pointing to a specific file (folder\\data.txt), but that doesn't work. I considered the ZipArchive class since it has a "CreateEntryFromFile" method, but it seems this only allows you to create an entry into an existing file.

Is there no way to simply zip up one file without creating an empty zipfile (which has its issues) and then using the ZipArchiveExtension's "CreateEntryFromFile" method?

**This is also assuming I am working on a company program which cannot use third-party add-ons at the moment.

example from: http://msdn.microsoft.com/en-us/library/ms404280%28v=vs.110%29.aspx

        string startPath = @"c:\example\start";
        string zipPath = @"c:\example\result.zip";
        string extractPath = @"c:\example\extract";

        ZipFile.CreateFromDirectory(startPath, zipPath);

        ZipFile.ExtractToDirectory(zipPath, extractPath);

But if startPath were to be @"c:\\example\\start\\myFile.txt;" , it would throw an error that the directory is invalid.

Answer 1

Use the CreateEntryFromFile off a an archive and use a file or memory stream:

Using a filestream if you are fine creating the zip file and then adding to it:

using (FileStream fs = new FileStream(@"C:\Temp\output.zip",FileMode.Create))
using (ZipArchive arch = new ZipArchive(fs, ZipArchiveMode.Create))
{
    arch.CreateEntryFromFile(@"C:\Temp\data.xml", "data.xml");
}

Or if you need to do everything in memory and write the file once it is done, use a memory stream:

using (MemoryStream ms = new MemoryStream())
using (ZipArchive arch = new ZipArchive(ms, ZipArchiveMode.Create))
{
    arch.CreateEntryFromFile(@"C:\Temp\data.xml", "data.xml");
}

Then you can write the MemoryStream to a file .

using (FileStream file = new FileStream("file.bin", FileMode.Create, System.IO.FileAccess.Write)) {
   byte[] bytes = new byte[ms.Length];
   ms.Read(bytes, 0, (int)ms.Length);
   file.Write(bytes, 0, bytes.Length);
   ms.Close();
}

Answer 2

Using file (or any) stream:

using (var zip = ZipFile.Open("file.zip", ZipArchiveMode.Create))
{
    var entry = zip.CreateEntry("file.txt");
    entry.LastWriteTime = DateTimeOffset.Now;

    using (var stream= File.OpenRead(@"c:\path\to\file.txt"))
    using (var entryStream = entry.Open())
        stream.CopyTo(entryStream);
}

or briefer:

// reference System.IO.Compression
using (var zip = ZipFile.Open("file.zip", ZipArchiveMode.Create))
    zip.CreateEntryFromFile("file.txt", "file.txt");

make sure you add references to System.IO.Compression

Update

Also, check out the new dotnet API documentation for ZipFile and ZipArchive too. There are a few examples there. There is also a warning about referencing System.IO.Compression.FileSystem to use ZipFile .

To use the ZipFile class, you must reference the System.IO.Compression.FileSystem assembly in your project.

Answer 3

The simplest way to get this working is to use a temporary folder.

FOR ZIPPING:

1. Create a temp folder
2. Move file to folder
3. Zip folder
4. Delete folder

FOR UNZIPPING:

1. Unzip archive
2. Move file from temp folder to your location
3. Delete temp folder

Answer 4

In .NET, there are quite a few ways to tackle the problem, for a single file. If you don't want to learn everything there, you can get an abstracted library, like SharpZipLib (long standing open source library), sevenzipsharp (requires 7zip libs underneath) or DotNetZip.

Answer 5

just use following code for compressing a file.

public void Compressfile()
        {
             string fileName = "Text.txt";
             string sourcePath = @"C:\SMSDBBACKUP";
             DirectoryInfo di = new DirectoryInfo(sourcePath);
             foreach (FileInfo fi in di.GetFiles())
             {
                 //for specific file 
                 if (fi.ToString() == fileName)
                 {
                     Compress(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());
                        }
                    }
                }
            }
        }

    }