CREATE ZIP FILE IN ASP.NET

public class Zip
{
public Zip()
{
}
static string writetofilepath = System.Web.HttpContext.Current.Server.MapPath("~/Files/");
public static void WriteZipFile(string[] filesToZip, string writeToFilePath)
{
try
{
if (EnsureDirectory(writetofilepath))
{
Crc32 crc = new Crc32();
FileStream fs1 = File.Create(writeToFilePath);
ZipOutputStream s = new ZipOutputStream(fs1);
s.SetLevel(9); // 0 - store only to 9 - means best compression
for (int i = 0; i < filesToZip.Length; i++)
{
      // Must use a relative path here so that files show up in the Windows Zip File Viewer
      // .. hence the use of Path.GetFileName(...)
ZipEntry entry = new ZipEntry(Path.GetFileName(writetofilepath + filesToZip[i]));
entry.DateTime = DateTime.Now;
// Read in the
using (FileStream fs = File.OpenRead(writetofilepath + filesToZip[i]))
{
byte[] buffer = new byte[fs.Length];
fs.Read(buffer, 0, buffer.Length);
      // set Size and the crc, because the information
      // about the size and crc should be stored in the header
      // if it is not set it is automatically written in the footer.
      // (in this case size == crc == -1 in the header)
      // Some ZIP programs have problems with zip files that don't store
      // the size and crc in the header.
entry.Size = fs.Length;
fs.Close();
crc.Reset();
crc.Update(buffer);
entry.Crc = crc.Value;
s.PutNextEntry(entry);
s.Write(buffer, 0, buffer.Length);
}
}
s.Finish();
s.Close();
}
}
catch (Exception ex)
{
HttpContext.Current.Trace.Warn(ex.ToString());
}
}
private static bool EnsureDirectory(string path)
{
if (!Directory.Exists(path))
{
Directory.CreateDirectory(path);
}
return true;
}
public string[] getdir()
{
DirectoryInfo di = new DirectoryInfo(writetofilepath);
FileInfo[] rgFiles = di.GetFiles("*.pdf");
string[] files = new string[rgFiles.Length];
int i = 0;
foreach (FileInfo fi in rgFiles)
{
files[i] = fi.Name;
 i++;
 }
 return files;
 }
 }