Help me in solving PLSQL15 problem

help
,
1

My issue

I declare a start_str and v_len for store len of string thenb iterate a onebyone ant store it in and

My code

DECLARE
    v_input_string VARCHAR2(100) := 'Hello, World!'; -- Input string
    v_output_string VARCHAR2(100) := '';    -- Reversed string
    v_len number := 13;
    start_str number := 0;
    
BEGIN
    LOOP
        v_output_string := v_output_string + SUBSTR(v_input_string,(v_len - start_str),1);
        start_str := start_str + 1;
        exit when start_str >= v_len;
    end LOOP;
    -- Output the reversed string
    DBMS_OUTPUT.PUT_LINE('Original String: ' || v_input_string);
    DBMS_OUTPUT.PUT_LINE('Reversed String: ' || v_output_string);
END;
/

Learning course: Learn Procedural SQL
Problem Link: Practice - Reverse a string in Procedural SQL

2

You need to use || symbol to append the string.

This code works:

DECLARE
    v_input_string VARCHAR2(100) := 'Hello, World!'; -- Input string
    v_output_string VARCHAR2(100) := '';    -- Reversed string
    v_len number := 13;
    start_str number := 0;
    
BEGIN
    LOOP
        v_output_string := v_output_string || SUBSTR(v_input_string,(v_len - start_str),1);
        start_str := start_str + 1;
        exit when start_str >= v_len;
    end LOOP;
    -- Output the reversed string
    DBMS_OUTPUT.PUT_LINE('Original String: ' || v_input_string);
    DBMS_OUTPUT.PUT_LINE('Reversed String: ' || v_output_string);
END;
/