How to get the ContentType of the File

private string GetContentType(string fileName)

{

string contentType = "application/octetstream";

string ext = System.IO.Path.GetExtension(fileName).ToLower();

Microsoft.Win32.RegistryKey registryKey = Microsoft.Win32.Registry.ClassesRoot.OpenSubKey(ext);

if (registryKey != null && registryKey.GetValue("Content Type") != null)

contentType = registryKey.GetValue("Content Type").ToString();

return contentType;

}