confused between dbms_output.put_line and dbms_output.put pl/sql - oracle

Question

i was trying to make something like this
when input : 5
it will print
A B C D E
input : 10
print
A B C D E
J I H G F
input : 15
print
A B C D E
J I H G F
K L M N O
input : 20
A B C D E
J I H G F
K L M N O
T S R Q P
and so on...
here is my code i create
declare
angka number := '&Angka';
i number := trunc(angka/5);
p number := 65;
a number := 1;
b number := 1;
begin
while a <= b loop
if mod(i,2) = 1 then
a := 5;
for b in 1..5 loop
p := p + a
dbms_output.put( chr(p) || ' ' );
a := a - 1;
end loop;
p := p + 5;
else
a := 1;
for b in 1..5 loop
p := p + a
dbms_output.put( chr(p) || ' ' );
a := a + 1;
end loop;
end loop;
dbms_output.put_line(' ');
end;
/
but i was still confused it's still didn't work
and about dbms_output.put_line vs dbms_output.put can someone explain this ? because i was trying print using dbms_output.put it's didn't show.. i don't know why
Thanks

Answer 1

Firstly, the line p := p + a has not been terminated by semi-colon. Ideally, the PL/SQL anonymous block shouldn't compile at first place.
Secondly, with PUT procedure, you haven't completed the line yet. It needs GET_LINES to retrieve an array of lines from the buffer.
There was a similar question, Is dbms_output.put() being buffered differently from dbms_output.put_line()?

Answer 2

You have some problems in your code. I don't believe that you can execute exactly this code. Propably, you forgot to copy some parts of it.
First of all, syntax errors:
declare
angka number := '&Angka';
i number := trunc(angka/5);
p number := 65;
a number := 1;
b number := 1;
begin
while a <= b loop
if mod(i,2) = 1 then
a := 5;
for b in 1..5 loop
p := p + a -- ";" missed
dbms_output.put( chr(p) || ' ' );
a := a - 1;
end loop;
p := p + 5;
else
a := 1;
for b in 1..5 loop
p := p + a -- ";" missed
dbms_output.put( chr(p) || ' ' );
a := a + 1;
end loop;
-- here you missed "end if"
end loop;
dbms_output.put_line(' ');
end;
/
Also you don't need your outer loop ("while a <= b loop"), because its condition always is true and code execution will never ends. And last - when you declare
for b in 1..5 loop
oracle creates here new variable with name "b", and inside the loop previously declared b is not visible. Try to execute this:
declare
b number := 111;
begin
for b in 1..5 loop
dbms_output.put_line(b);
end loop;
dbms_output.put_line(b);
end;
/
You will get:
1
2
3
4
5
111
If you correct these errors, your code will work as you want.