sub set_datetime_str
{
    local ($wkstr) = $_[0];
    local ($outStr) = "";
    local ($fday, $fmon, $fyea, $fhou, $fmin, $fsec);

    # format should be: `date "+%d-%m-%Y %H:%M:%S"`;

    $fday=substr($wkstr,0,2); 
    $fmon=substr($wkstr,3,2); 
    $fyea=substr($wkstr,6,4); 
    $fhou=substr($wkstr,11,2); 
    $fmin=substr($wkstr,14,2); 
    $fsec=substr($wkstr,17,2); 

    # format for order criteria

    $outStr=$fyea.$fmon.$fday.$fhou.$fmin.$fsec ;
  return $outStr;
}

sub get_datetime_str
{
    local ($wkstr) = $_[0];
    local ($outStr) = "";
    local ($fday, $fmon, $fyea, $fhou, $fmin, $fsec);

    # format should be: `date "+%d-%m-%Y %H:%M:%S"`;

    $fday=substr($wkstr,6,2); 
    $fmon=substr($wkstr,4,2); 
    $fyea=substr($wkstr,0,4); 
    $fhou=substr($wkstr,8,2); 
    $fmin=substr($wkstr,10,2); 
    $fsec=substr($wkstr,12,2); 

    # format for order criteria

    $outStr=$fday."-".$fmon."-".$fyea." ".$fhou.":".$fmin.":".$fsec ;

  return $outStr;
}
