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Compress & Decompress Strings In C#
By Mads Kristensen
Expert Author
Article Date: 2007-05-03
A couple of days ago, I had to store some very big strings in an XML file.
To keep the file size down I wanted to compress the strings using a GZipStream and then decompress them later when needed.
I modified the methods from Papenoo pa so they handled strings in stead of byte arrays.
using System.IO.Compression;
using System.Text;
using System.IO;
publicstaticstring Compress(string text)
{
byte[] buffer = Encoding.UTF8.GetBytes(text);
MemoryStream ms =new MemoryStream();
using (GZipStream zip =new GZipStream(ms, CompressionMode.Compress, true))
{
zip.Write(buffer, 0, buffer.Length);
}
ms.Position = 0;
MemoryStream outStream =new MemoryStream();
byte[] compressed =newbyte[ms.Length];
ms.Read(compressed, 0, compressed.Length);
byte[] gzBuffer =newbyte[compressed.Length + 4];
System.Buffer.BlockCopy(compressed, 0, gzBuffer, 4, compressed.Length);
System.Buffer.BlockCopy(BitConverter.GetBytes(buffer.Length), 0, gzBuffer, 0, 4);
return Convert.ToBase64String (gzBuffer);
}
publicstaticstring Decompress(string compressedText)
{
byte[] gzBuffer = Convert.FromBase64String(compressedText);
using (MemoryStream ms =new MemoryStream())
{
int msgLength = BitConverter.ToInt32(gzBuffer, 0);
ms.Write(gzBuffer, 4, gzBuffer.Length - 4);
byte[] buffer =newbyte[msgLength];
ms.Position = 0;
using (GZipStream zip =new GZipStream(ms, CompressionMode.Decompress))
{
zip.Read(buffer, 0, buffer.Length);
}
return Encoding.UTF8.GetString(buffer);
}
}
The strings need to be longer than 3-400 characters; otherwise the compression rate is not good enough.
Comments
About the Author:
Mads Kristensen currently works as a Senior Developer at Traceworks located
in Copenhagen, Denmark. Mads graduated from Copenhagen Technical Academy with a multimedia degree in
2003, but has been a professional developer since 2000. His main focus is on ASP.NET but is responsible for Winforms, Windows- and
web services in his daily work as well. A true .NET developer with great passion for the simple solution.
http://www.madskristensen.dk/
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