ChineseDecode.cs

using System;
using System.Text;
using System.IO;

namespace ChineeseDecode
{
	class Program
	{
		static void main( string path )
		{
			Encoding enc = Encoding.GetEncoding( 936 ); // Codepage #936 "Chinese Main Land"
			string all;
			using( var f = new StreamReader( path, enc ) )
				all = f.ReadToEnd();
			File.Delete( path );
			using( var f = new StreamWriter( path, false, Encoding.UTF8 ) )
				f.Write( all );
		}

		static void Main( string[] args )
		{
			try
			{
				main( args[ 0 ] );
			}
			catch( Exception ex )
			{
				Console.WriteLine( ex.Message );
			}
		}
	}
}