private LONG _Reg_EnumKeyName(  in    HKEY    hkey
                             ,  in    DWORD   dwIndex
                             ,  in    LPSTR   lpName
                             ,  inout DWORD   cchName)

in

{
    assert(null !== hkey);
}
body
{
    FILETIME    ftLastWriteTime;
    return RegEnumKeyExA(hkey, dwIndex, lpName, cchName
                  , RESERVED, null, null, &ftLastWriteTime);
}

class KeyNameSequence
{
public:
  char[] GetKeyName(in uint index)
  {
    DWORD   cSubKeys;
    DWORD   cchSubKeyMaxLen;
    HKEY    hkey  = m_key.m_hkey;
    LONG    res   = _Reg_GetNumSubKeys(hkey, cSubKeys, cchSubKeyMaxLen);
    char[]  sName = new char[1 + cchSubKeyMaxLen];
    DWORD   cchName;
    res = _Reg_EnumKeyName(hkey, index, sName, cchName);
    assert(ERROR_MORE_DATA != res);
    if(ERROR_SUCCESS != res)
    {
        throw new RegistryException("Invalid key", res);
    }
    return sName[0 .. cchName];
  }
  ...

private LONG _Reg_GetNumSubKeys(  in  HKEY  hkey
                                , out DWORD cSubKeys
                                , out DWORD cchSubKeyMaxLen);

Example 1: (a) The definition for helper function _Reg_EnumKeyName(); (b) methods of several of the classes in the registry module; (c) determining the number of subkeys and the maximum length of the names of the subkeys.