SQL> SELECT NAME FROM V$DATAFILE;

NAME                                                                            
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C:\ORACLEXE\ORADATA\XE\SYSTEM.DBF                                               
C:\ORACLEXE\ORADATA\XE\UNDO.DBF                                                 
C:\ORACLEXE\ORADATA\XE\SYSAUX.DBF                                               
C:\ORACLEXE\ORADATA\XE\USERS.DBF                                                

SQL> spool off