Unzip files programmatically in .net

Question

Hi,

I am trying to programatically unzip a zipped file.

I hace tried using the System.IO.Compression.GZipStream class in .NET, but when my app runs (actually an unit test) I get this expection:

System.IO.InvalidDataException: The magic number in GZip header is not correct. Make sure you are passing in a GZip stream..

I now realize that a .zip file is not the same as a .gz file, and that GZip is not the same as Zip.

However, since I'm able to extract the file by manually double clicking the zipped file and then clicking the "Extract all files"-button, I think there should be a way of doing that in code also.

Therefore I've tried to use Process.Start() with the path to the zipped file as input. This causes my app to open a Window showing the contents in the zipped file. That's all fine, but the app will be installed on a server with noone around to click the "Extract all files"-button.

So, how do I get my app to extract the files in the zipped files?

Or is there another way to do it? I prefer doing it in code, without downloading any third party libraries or apps; the security department ain't too fancy about that...

Answer 1

Use the DotNetZip library at http://www.codeplex.com/DotNetZip

Answer 2

Standard zip files normally use the deflate algorithm.

To extract files without using third party libraries use DeflateStream. You'll need a bit more information about the zip file archive format as Microsoft only provides the compression algorithm.

You may also try using zipfldr.dll. It is Microsoft's compression library (compressed folders from the Send to menu). It appears to be a com library but it's undocumented. You may be able to get it working for you through experimentation.

Answer 3

From here :

Compressed GZipStream objects written to a file with an extension of .gz can be decompressed using many common compression tools; however, this class does not inherently provide functionality for adding files to or extracting files from .zip archives.

Answer 4

You haven't specified which version of .Net you are using, but there's a (dirty) way to do this: Visual J# includes a MS implementation of java.util.zip...

See this article for details on that

Answer 5

We have used SharpZipLib successfully on many projects. I know it's a third party tool, but source code is included and could provide some insight if you chose to reinvent the wheel here.

Answer 6

I found sample code to unzip files in .net c#