How to iterate over binary string in Oracle? - sql

Question

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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 string and behaves very unusually.Please suggest some good approaches to iterate over binary strings like this.I am expecting output as 4,5,6 from above operation.
EDIT1:
Please don't directly input the string as str varchar2(2000) := '000111000';
Instead input it from bind variable as I mentioned above.

Answer 1

Your code works so long as you pass in a VARCHAR2 data type (and not a NUMBER).
You can also tidy up the code passing in the bind variable only once and using CONSTANTs to hold the values that are constant:
VARIABLE in_string VARCHAR2;
DECLARE
c_string CONSTANT VARCHAR2(200) := :in_string;
c_length CONSTANT PLS_INTEGER := LENGTH(c_string);
v_out CHAR(1);
BEGIN
FOR i IN 1..c_length
LOOP
v_out := SUBSTR(c_string,i,1) ;
DBMS_OUTPUT.PUT_LINE(v_out);
END LOOP;
END;
/
Which outputs:
0
0
1
1
1
0
0
0
db<>fiddle here

Answer 2

Shouldn't behave unusual, unless datatype of in_string variable is NUMBER (then leading zeros don't have any meaning) - switch to VARCHAR2.
Illustration:
NUMBER variable datatype
value you enter
result - really, missing leading zeros
Otherwise, it works OK (this is SQL*Plus so I used substitution variable):
SQL> DECLARE
2 v_length NUMBER (10);
3 v_out VARCHAR2 (20);
4 BEGIN
5 v_length := LENGTH ( '&&in_string');
6
7 FOR i IN 1 .. v_length
8 LOOP
9 v_out := SUBSTR ( '&&in_string', i, 1);
10 DBMS_OUTPUT.PUT_LINE (v_out);
11 END LOOP;
12 END;
13 /
Enter value for in_string: 00111000
0
0
1
1
1
0
0
0
PL/SQL procedure successfully completed.
Another option (if you're interested in it) doesn't require PL/SQL:
SQL> SELECT SUBSTR ( '&&in_string', LEVEL, 1) val
2 FROM DUAL
3 CONNECT BY LEVEL <= LENGTH ( '&&in_string');
V
-
0
0
1
1
1
0
0
0
8 rows selected.
SQL>