How to check free space in each datafile for each tablespace

How to check free space in each datafile for each tablespace

break on table_space on free
col tablespace_name format a15
col file_name format format a50
col free_bytes format 999,999,999,990
col bytes allocated_bytes format 999,999,999,990
set pagesize 66
set lines 100

SELECT
   a.tablespace_name,
   a.file_name,
   a.bytes allocated_bytes,
   b.free_bytes
FROM
   dba_data_files a,
   (SELECT file_id, SUM(bytes) free_bytes
    FROM dba_free_space b
    GROUP BY file_id) b
WHERE
   a.file_id=b.file_id
ORDER BY
   a.tablespace_name;