|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Announcements
Chapters
Services
Feature Zones
|
IntroductionThis article presents two methods to compress and decompress strings using Context/ProblemAfter converting code from VB.NET 1.1 to C#.NET 3.5, I needed to change some code using a third party zip class to GZipStream. Code samples found on the web or on VS help where presenting solutions dealing with FileStream but in this case, a string is given as an input parameter. So the little challenge was to go from a string to a byte array (byte[]) and vice versa without losing a char nor changing its encoding because I ended up finding that TipsSo as I found no method transforming a string into a byte[] and vice versa without involving encoding specifications, I ended up with a loop and a cast. If you have a better idea, please tell me so. And I found out, if you only flush a GZipStream instance and retrieve the data from the underlying stream without closing this GZipStream instance, you miss part of the data. The CodeCompress/Zip a string: public static string Zip(string value)
{
//Transform string into byte[]
byte[] byteArray = new byte[value.Length];
int indexBA = 0;
foreach (char item in value.ToCharArray())
{
byteArray[indexBA++] = (byte)item;
}
//Prepare for compress
System.IO.MemoryStream ms = new System.IO.MemoryStream();
System.IO.Compression.GZipStream sw = new System.IO.Compression.GZipStream(ms,
System.IO.Compression.CompressionMode.Compress);
//Compress
sw.Write(byteArray, 0, byteArray.Length);
//Close, DO NOT FLUSH cause bytes will go missing...
sw.Close();
//Transform byte[] zip data to string
byteArray = ms.ToArray();
System.Text.StringBuilder sB = new System.Text.StringBuilder(byteArray.Length);
foreach (byte item in byteArray)
{
sB.Append((char)item);
}
ms.Close();
sw.Dispose();
ms.Dispose();
return sB.ToString();
}
Decompress/Unzip a string: input value has been previously compressed with GZipStream. public static string UnZip(string value)
{
//Transform string into byte[]
byte[] byteArray = new byte[value.Length];
int indexBA = 0;
foreach (char item in value.ToCharArray())
{
byteArray[indexBA++] = (byte)item;
}
//Prepare for decompress
System.IO.MemoryStream ms = new System.IO.MemoryStream(byteArray);
System.IO.Compression.GZipStream sr = new System.IO.Compression.GZipStream(ms,
System.IO.Compression.CompressionMode.Decompress);
//Reset variable to collect uncompressed result
byteArray = new byte[byteArray.Length];
//Decompress
int rByte = sr.Read(byteArray, 0, byteArray.Length);
//Transform byte[] unzip data to string
System.Text.StringBuilder sB = new System.Text.StringBuilder(rByte);
//Read the number of bytes GZipStream red and do not a for each bytes in
//resultByteArray;
for (int i = 0; i < rByte; i++)
{
sB.Append((char)byteArray[i]);
}
sr.Close();
ms.Close();
sr.Dispose();
ms.Dispose();
return sB.ToString();
}
Points of InterestWell, if you haven't dealt with a lot of streams like me, hopefully this will avoid loss of time!
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||