Reverse function in Oracle

The following shows how to use the reverse function to reverse a string or number in Oracle.
SQL> select reverse('string') from dual;
REVERS
------
gnirts

However you may not have the function installed and can use the following procedure:
SQL>
SQL> create or replace procedure reverse(x in varchar2) as
2 a char(1);
3 i number;
4 begin
5 for i in 1..length(x) loop
6 select substr(x,length(x)-i+1,1) into c from dual;
7 dbms_output.put(a);
8 end loop;
9 dbms_output.put_line(' ');
10 end;
11 /


Procedure created.

SQL> set serverout on
SQL> exec reverse('Oracle')
elcarO

SQL> exec reverse('string')
gnirts
PL/SQL procedure successfully completed.