How do I create 7-Zip archives with .NET?

EggCafe 7Zip cookie example This is an example (zipping cookie) with the DLL of 7Zip.

CodePlex Wrapper This is an open source project that warp zipping function of 7z.

7Zip SDK The official SDK for 7zip (C, C++, C#, Java) <---My suggestion

.Net zip library by SharpDevelop.net

CodeProject example with 7zip

SharpZipLib Many zipping

If you can guarantee the 7-zip app will be installed (and in the path) on all target machines, you can offload by calling the command line app 7z. Not the most elegant solution but it is the least work.

SevenZipSharp is another solution. Creates 7-zip archives...

I used the sdk.

eg:

using SevenZip.Compression.LZMA;
private static void CompressFileLZMA(string inFile, string outFile)
{
   SevenZip.Compression.LZMA.Encoder coder = new SevenZip.Compression.LZMA.Encoder();

   using (FileStream input = new FileStream(inFile, FileMode.Open))
   {
      using (FileStream output = new FileStream(outFile, FileMode.Create))
      {
          coder.Code(input, output, -1, -1, null);
          output.Flush();
      }
   }
}

Some additional test-info on @Orwellophile code using a 17.9MB textfile.
Using the property values in the code-example "as is" will have a HUGE negative impact on performance, it takes 14.16 sec.

Setting the properties to the following do the same job at 3.91 sec (i.a. the archive will have the same container info which is: you can extract and test the archive with 7zip but there are no filename information)

Native 7zip 2 sec.

CoderPropID[] propIDs =  {
  //CoderPropID.DictionarySize,
  //CoderPropID.PosStateBits,
  //CoderPropID.LitContextBits,
  //CoderPropID.LitPosBits,
  //CoderPropID.Algorithm,
  //CoderPropID.NumFastBytes,
  //CoderPropID.MatchFinder,
  CoderPropID.EndMarker
};
object[] properties = {
  //(Int32)(dictionary),
  //(Int32)(posStateBits),
  //(Int32)(litContextBits),
  //(Int32)(litPosBits),
  //(Int32)(algorithm),
  //(Int32)(numFastBytes),
  //mf,
  eos
};

I did another test using native 7zip and a 1,2GB SQL backup file (.bak)
7zip (maximum compression): 1 minute
LZMA SDK (@Orwellophile with above property-setting): 12:26 min :-(
Outputfile roughly same size.

So I guess I'll myself will use a solution based on the c/c++ engine, i.a. either call the 7zip executable from c# or use squid-box/SevenZipSharp, which is a wrapper around the 7zip c/c++ dll file, and seems to be the newest fork of SevenZipSharp. Haven't tested the wrapper, but I hope is perform just as the native 7zip. But hopefully it will give the possibility to compress stream also which you obvious cannot if you call the exe directly. Otherwise I guess there isn't mush advantage over calling the exe. The wrapper have some additional dependencies so it will not make your published project "cleaner".

By the way it seems the .Net Core team consider implementing LZMA in the system.io class in .Core ver. 5, that would be great!

(I know this is kind of a comment and not an answer but to be able to provide the code snippet it couldn't be a comment)

Install the NuGet package called SevenZipSharp.Interop

Then:

SevenZipBase.SetLibraryPath(@".\x86\7z.dll");
var compressor = new SevenZip.SevenZipCompressor();
var filesToCompress = Directory.GetFiles(@"D:\data\");
compressor.CompressFiles(@"C:\archive\abc.7z", filesToCompress);

SharpCompress is in my opinion one of the smartest compression libraries out there. It supports LZMA (7-zip), is easy to use and under active development.

As it has LZMA streaming support already, at the time of writing it unfortunately only supports 7-zip archive reading. BUT archive writing is on their todo list (see readme). For future readers: Check to get the current status here: https://github.com/adamhathcock/sharpcompress/blob/master/FORMATS.md

Here is code to create and extract 7zip (based on LZMA SDK - C#)

Note: 7z archives created with same code can be unarchived. As code uses managed LZMA using earlier version of LZMA SDK