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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.