Getting Mime types and file extensions from registry using C#

If you have a mime type and you want to find the default extension for this mime type, you can get this from the following registry key
HKEY_CLASSES_ROOT\MIME\Database\Content Type\<mime type>

public static string GetDefaultExtension(string mimeType)

{

  string result;

  RegistryKey key;

  object value;

  key = Registry.ClassesRoot.OpenSubKey("MIME\Database\Content Type\" + mimeType, false);

  value = key != null ? key.GetValue("Extension", null) : null;

  result = value != null ? value.ToString() : string.Empty;

  return result;

}

on the other hand, if you have the file extension and you want the mime type of this extension

HKEY_CLASSES ROOT\<extension>

public static string GetMimeTypeFromExtension(string extension)

{

  string result;

  RegistryKey key;

  object value;

  if (!extension.StartsWith("."))

    extension = "." + extension;

  key = Registry.ClassesRoot.OpenSubKey(extension, false);

  value = key != null ? key.GetValue("Content Type", null) : null;

  result = value != null ? value.ToString() : string.Empty;

  return result;

}




and this is all :)