SQL Developer

<img src="https://objectstorage.us-phoenix-1.oraclecloud.com/p/BqK85Rn1zA5MP0vYiqbAdPgs7Z6OmMxw8SD3WCFVm5kY8uReidZ1KPIKkgJ1hCkG/n/axciphqpnohg/b/forums-legacy/o/uploads/P4BZJ8P9M5UD/bugsqldev.png" alt="bugsqldev.png">declare

str varchar2(2000) := :inputstr;
v_len number;
currChar CHAR(1);

begin
                v_len := length(str);
                for i in 1..v_len
                Loop
                        currChar  := substr(str,i,1);
                        if currChar = 1 then
              dbms_output.put_line('curr index' || i);
                        end if;
                End loop;
end;

When I pass '000111000' as input to IN_STRING variable , it trims the left zeros from string.I am expecting output as 4,5,6 from above operation.