SQL> declare
  2    boo boolean := true;
  3  begin
  4  
  5   if boo then
  6      dbms_output.put_line('boolean variable value TRUE  by checking if condition ');
  7    end if;
  8    dbms_output.put_line(' Directly print the value Boolean variable value '|| boo);
  9  end;
 10  
 11  /
 
declare
  boo boolean := true;
begin

 if boo then
    dbms_output.put_line('boolean variable value TRUE  by checking if condition ');
  end if;
  dbms_output.put_line(' Directly print the value Boolean variable value '|| boo);
end;
 
ORA-06550: line 9, column 24:
PLS-00306: wrong number or types of arguments in call to '||'
ORA-06550: line 9, column 3:
PL/SQL: Statement ignored

  case boo
    when true then <the string "value" for TRUE>
    when false then <the string "value" for FALSE>
    else <the string "value" for NULL>
  end

SYS@orcl_11gR2> grant execute on sys.dbms_sqltcb_internal to scott
  2  /

Grant succeeded.

SYS@orcl_11gR2> connect scott/tiger
Connected.
SCOTT@orcl_11gR2> declare
  2    boo boolean;
  3  begin
  4    boo := true;
  5    dbms_output.put_line (case boo when true then 'true' when false then 'false' end);
  6    dbms_output.put_line (sys.dbms_sqltcb_internal.i_convert_from_boolean (boo));
  7    dbms_output.put_line (sys.diutil.bool_to_int (boo));
  8    boo := false;
  9    dbms_output.put_line (case boo when true then 'true' when false then 'false' end);
 10    dbms_output.put_line (sys.dbms_sqltcb_internal.i_convert_from_boolean (boo));
 11    dbms_output.put_line (sys.diutil.bool_to_int (boo));
 12  end;
 13  /
true
TRUE
1
false
FALSE
0

PL/SQL procedure successfully completed.