Oracle File Names | Numeric Ended | Data Files iteration

-- file_names that are not ended with numeric value after chr(59) _

select  file_name     
        from dba_data_files 
            where substr(file_name,1,instr(file_name,'.dbf')) like '%\_%' escape '\'
                and is_number(replace(substr (substr(file_name,1,instr(file_name,'.dbf')),instr(file_name,'_',1,(REGEXP_COUNT(file_name, '_', 1, 'i')))+1,100 ),'.','')) = 0

       
CREATE FUNCTION is_number (p_string IN VARCHAR2)
   RETURN INT
IS
   v_new_num NUMBER;
BEGIN
   v_new_num := TO_NUMBER(p_string);
   RETURN 1;
EXCEPTION
WHEN VALUE_ERROR THEN
   RETURN 0;
END is_number;