Difference between open,fetch,close and a for loop

Question

Is there much difference in looping a query using fetch loop or a for loop?
Example:
For x in (select * from ....) loop
end loop;
and
OPEN c_cursor;
LOOP
FETCH c_cursor INTO myVar;
EXIT WHEN c_cursor%NOTFOUND;
END LOOP;
close c_cursor;
Let's say we have a few thousand users using a function that uses this code. Would you see much difference in speed? Suppose i forget to close the cursor in the second example. Will that be a major issue if we have a very large userbase or with oracle close the cursor themself after a while? The cursor wont lock the record, right? So even if we forget to close the cursor we won't get a deadlock i suppose. Only if we declare the cursor for update but that's not the case.

Answer 1

simple test case to prove the point
SQL> create or replace function myFunc return number
  2  is
  3     cursor mycursor
  4     is
  5     select * from dual;
  6
  7     myvar dual.dummy%type;
  8  Begin
  9     open myCursor;
10
11     fetch myCursor into myVar;
12
13
14     if myCursor%found
15     then
16
17             return 1;
18     else
19             return 0;
20     end if;
21
22
23     close myCursor;
24  end;
25  /
Function created.
SQL> show parameter open_cursor
NAME                                 TYPE        VALUE
open_cursors                         integer     300
SQL>
SQL> select myfunc from dual connect by level <= 350
  2  /
    MYFUNC
         1
         1
         1
         1
         1
         1
         1
         1
         1
         1
         1
350 rows selected.
SQL>See i dont hit any error