Oracle - convert clob into varchar2

https://asktom.oracle.com/pls/asktom/f?p=100:11:0::NO::P11_QUESTION_ID:367980988799

create or replace procedure p ( p_str in varchar2 )
is
   l_str   long := p_str;
begin
   loop
      exit when l_str is null;
      dbms_output.put_line( substr( l_str, 1, 250 ) );
      l_str := substr( l_str, 251 );
   end loop;
end;
/