Introduction On Text Compression Using Lempel, Ziv, Welch (LZW) method

using System;

public class Compress
{
	private static System.String[] Files
	{
		set
		{
			System.String inputFile, outputFile;
			if (value.Length >= 1)
			{
				inputFile = value[0];
				in_Renamed = new System.IO.BufferedStream(new System.IO.FileStream(inputFile, System.IO.FileMode.Open, System.IO.FileAccess.Read));
				outputFile = inputFile + ".zzz";
				out_Renamed = new System.IO.BufferedStream(new System.IO.FileStream(outputFile, System.IO.FileMode.Create));
			}
			else
			{
				System.Console.Out.Write("usage:java Compress ");
				System.Environment.Exit(1);
			}
		}
		
	}
	internal const int MAX_CODES = 4096;
	internal const int BYTE_SIZE = 8;
	internal const int EXCESS = 4;
	internal const int ALPHA = 256;
	internal const int MASK1 = 255;
	internal const int MASK2 = 15;
	
	internal static int leftOver;
	internal static bool bitsLeftOver;
	internal static System.IO.BufferedStream in_Renamed;
	internal static System.IO.BufferedStream out_Renamed;
	
	private static void  output(int pcode)
	{
		int c, d;
		if (bitsLeftOver)
		{
			d = pcode & MASK1;
			c = (leftOver << EXCESS) + (pcode >> BYTE_SIZE);
			out_Renamed.WriteByte((System.Byte) c);
			out_Renamed.WriteByte((System.Byte) d);
			bitsLeftOver = false;
		}
		else
		{
			leftOver = pcode & MASK2;
			c = pcode >> EXCESS;
			out_Renamed.WriteByte((System.Byte) c);
			bitsLeftOver = true;
		}
	}
	
	private static void  compress()
	{
		System.Collections.Hashtable table = new System.Collections.Hashtable();
		for (int i = 0; i < ALPHA; i++)
			SupportClass.PutElement(table, i, i);
		
		int codeUsed = ALPHA;
		
		int c = in_Renamed.ReadByte();
		if (c != - 1)
		{
			int pcode = c;
			c = in_Renamed.ReadByte();
			while (c != - 1)
			{
				int k = (pcode << BYTE_SIZE) + c;
				System.Int32 e = (System.Int32) table[k];
				if ((System.Object) e == null)
				{
					output(pcode);
					if (codeUsed < MAX_CODES)
						SupportClass.PutElement(table, (pcode << BYTE_SIZE) + c, codeUsed++);
					pcode = c;
				}
				else
					pcode = e;
				c = in_Renamed.ReadByte();
			}
			
			output(pcode);
			if (bitsLeftOver)
				out_Renamed.WriteByte((System.Byte) (leftOver << EXCESS));
		}
		//UPGRADE_TODO: Method 'java.io.BufferedInputStream.close' was not converted. 'ms-help://MS.VSCC.2003/commoner/redir/redirect.htm?keyword="jlca1095"'
		//System.IO.BufferedStream.Null ; 
		in_Renamed.Close(); 
		out_Renamed.Close();
	}
	
	[STAThread]
	public static void  Main(System.String[] args)
	{
		Files = args;
		compress();
	}
}

using System;

public class Decompress
{
	private static System.String[] Files
	{
		set
		{
			System.String inputFile, outputFile;
			if (value.Length >= 1)
			{
				inputFile = value[0];
				if (!inputFile.EndsWith(".zzz"))
				{
					System.Console.Out.WriteLine("The filename must end with \"zzz\" extension");
					System.Environment.Exit(1);
				}
				in_Renamed = new System.IO.BufferedStream(new System.IO.FileStream(inputFile, System.IO.FileMode.Open, System.IO.FileAccess.Read));
				outputFile = inputFile.Substring(0, (inputFile.Length - 4) - (0));
				out_Renamed = new System.IO.BufferedStream(new System.IO.FileStream(outputFile, System.IO.FileMode.Create));
			}
			else
			{
				System.Console.Out.Write("usage:java Decompress ");
				System.Environment.Exit(1);
			}
		}
		
	}
	private static int Code
	{
		get
		{
			int c = in_Renamed.ReadByte();
			if (c == - 1)
				return - 1;
			
			int code;
			if (bitsLeftOver)
				code = (leftOver << BYTE_SIZE) + c;
			else
			{
				int d = in_Renamed.ReadByte();
				code = (c << EXCESS) + (d >> EXCESS);
				leftOver = d & MASK;
			}
			bitsLeftOver = !bitsLeftOver;
			return code;
		}
		
	}
	
	internal const int MAX_CODES = 4096;
	internal const int BYTE_SIZE = 8;
	internal const int EXCESS = 4;
	internal const int ALPHA = 256;
	internal const int MASK = 15;
	
	internal static int[] s;
	internal static int size;
	internal static Element[] h;
	internal static int leftOver;
	internal static bool bitsLeftOver;
	internal static System.IO.BufferedStream in_Renamed;
	internal static System.IO.BufferedStream out_Renamed;
	
	private static void  output(int code)
	{
		size = - 1;
		while (code >= ALPHA)
		{
			s[++size] = h
.suffix;
			code = h
.prefix;
		}
		s[++size] = code;
		for (int i = size; i >= 0; i--)
			out_Renamed.WriteByte((System.Byte) s[i]);
	}
	
	private static void  decompress()
	{
		int codeUsed = ALPHA;
		s = new int[MAX_CODES];
		h = new Element[MAX_CODES];
		
		int pcode = Code, ccode;
		if (pcode >= 0)
		{
			s[0] = pcode;
			out_Renamed.WriteByte((System.Byte) s[0]);
			size = 0;
			
			do 
			{
				ccode = Code;
				if (ccode < 0)
					break;
				if (ccode < codeUsed)
				{
					output(ccode);
					if (codeUsed < MAX_CODES)
						h[codeUsed++] = new Element(pcode, s[size]);
				}
				else
				{
					h[codeUsed++] = new Element(pcode, s[size]);
					output(ccode);
				}
				pcode = ccode;
			}
			while (true);
		}
		out_Renamed.Close();
		//UPGRADE_TODO: Method 'java.io.BufferedInputStream.close' was not converted. 'ms-help://MS.VSCC.2003/commoner/redir/redirect.htm?keyword="jlca1095"'
		in_Renamed.Close();
	}
	
	[STAThread]
	public static void  Main(System.String[] args)
	{
		Files = args;
		decompress();
	}
}

--------------------------
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SupportClass.cs

//
// In order to convert some functionality to Visual C#, the Java Language Conversion Assistant
// creates "support classes" that duplicate the original functionality.  
//
// Support classes replicate the functionality of the original code, but in some cases they are 
// substantially different architecturally. Although every effort is made to preserve the 
// original architecture of the application in the converted project, the user should be aware that 
// the primary goal of these support classes is to replicate functionality, and that at times 
// the architecture of the resulting solution may differ somewhat.
//

using System;

/// 

/// Contains conversion support elements such as classes, interfaces and static methods.
/// 

public class SupportClass
{
	/// 

	/// Adds a new key-and-value pair into the hash table
	/// 

	/// The collection to work with
	/// Key used to obtain the value
	/// Value asociated with the key
	/// The old element associated with the key
	public static System.Object PutElement(System.Collections.IDictionary collection, System.Object key, System.Object newValue)
	{
		System.Object element = collection[key];
		collection[key] = newValue;
		return element;
	}

}



Element.cs

using System;
class Element
{
	internal int prefix;
	internal int suffix;
	
	public Element(int prefix, int suffix)
	{
		this.prefix = prefix;
		this.suffix = suffix;
	}
}