[
  {
    "Id": "671680",
    "ThreadId": "272554",
    "Html": "\r\n<p>I have some XML data which is returned as a string from a HTTP request. The string is compress using gzip and needs uncompressing.</p>\r\n<p>I have implemented the following method to achieve this but keep getting an error:</p>\r\n<p>&nbsp;public static string DecompressString(string zippedString)<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; string result = string.Empty;</p>\r\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; using (MemoryStream ms = new MemoryStream(Encoding.UTF8.GetBytes(zippedString)))<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ms.Position = 0;<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; using (ZipFile zip = ZipFile.Read(ms))<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; if (zip.Count &gt; 0)<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ZipEntry entry = zip[0]; // there should only be one entry</p>\r\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; if (entry != null)<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; using (MemoryStream output = new MemoryStream())<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; {<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; entry.Extract(output);<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; output.Position = 0;</p>\r\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; StreamReader sr = new StreamReader(output);<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; result = sr.ReadToEnd();<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }</p>\r\n<p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; return result;<br>\r\n&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }</p>\r\n<p>The error I get is: zipentry::readheader(): bad signature (0xb980e21f) at position&nbsp; 0x00000000&quot; which occurs then I attempt to read the memory stream</p>\r\n<div id=\"_mcePaste\" style=\"width:1px; height:1px; overflow:hidden; top:0px; left:-10000px\">\r\n&#65279;</div>\r\n",
    "PostedDate": "2011-09-14T06:05:54.317-07:00",
    "UserRole": null,
    "MarkedAsAnswerDate": null
  },
  {
    "Id": "671847",
    "ThreadId": "272554",
    "Html": "<p>ok, first thing - if you are using HttpWebRequest to retrieve the information, you can easily enable automatic decompression, without using DotNetZip or any decompression library.&nbsp;&nbsp; Check this:&nbsp; <a href=\"http://stackoverflow.com/questions/2815721/net-is-it-possible-to-get-httpwebrequest-to-automatically-decompress-gzipd-res\">http://stackoverflow.com/questions/2815721/net-is-it-possible-to-get-httpwebrequest-to-automatically-decompress-gzipd-res</a></p>\r\n<p>But you said that it is an XML file, and there's a string involved, and so on, so I'm not sure that will apply to you.</p>\r\n<p>Next: If you have data that is GZip'd then you cannot use ZipFile to decompress it.&nbsp; GZIP is a different format, and you cannot read a GZip stream using DotNetZip's ZipFile class.&nbsp; There is a class in the DotNetZip library for compressing and decompressing a GZip - Ionic.Zlib.GZipStream.&nbsp; If you need to decompress manually&nbsp; - if the automatic decompression I mentioned above does not work - then use GZipStream, not ZipFile.</p>\r\n<p>Last thing: I don't know where you got your zippedString, but I am certain that You cannot call <strong>Encoding.UTF8.GetBytes(zippedString) </strong>and expect to get a byte array that is GZIP compressed.&nbsp; Calling GetBytes() on it will not give you anything that GZipStream can read.&nbsp; You need to do a little more research on exactly how that zippedString is created.&nbsp; I suppose it may be a string which results from applying a transformation to an array of bytes.&nbsp; In some cases an app will base64-encode array of bytes in order to transform it into a printable string.&nbsp; In other cases an&nbsp; app will hex encode the original data. There are other options.&nbsp; You need to understand the transformation that was applied to the original data in order to get the zippedString thing, and apply the reverse transformation in your app to&nbsp;recover the initial data.&nbsp; Base64-<em>decode </em>or hex-<em>decode</em>, or etc. Then you will have an array of bytes.&nbsp; The next step is to apply the reverse transformation to that byte array - in your case that could be GZip decompression, which, as I said above, you can do with the GZipStream. &nbsp;</p>\r\n<p>&nbsp;</p>",
    "PostedDate": "2011-09-14T11:26:51.027-07:00",
    "UserRole": null,
    "MarkedAsAnswerDate": null
  },
  {
    "Id": "672138",
    "ThreadId": "272554",
    "Html": "<p>Thanks for the reply, I have the auto decompression working fine now.</p>",
    "PostedDate": "2011-09-15T01:51:41.35-07:00",
    "UserRole": null,
    "MarkedAsAnswerDate": null
  }
]