I am trying to write a program for Armstrong number in PL/SQL.Can anyone tell me where i am wrong?

Question

while  N !=0
LOOP

R:=MOD(N,10);
R1:=power(R,3);
A:=A+R1;
N:=TRUNC(N/10);

END LOOP;

After this it comes IF N=A THEN SYS.DBMS_OUTPUT.PUT_LINE(' number is armstrong '); ELSE SYS.DBMS_OUTPUT.PUT_LINE(' number is not an armstrong ');

Answer 1

Your problem is when you compare (N=A) because N is zero at the end of LOOP. Then you must compare A with the original number entered, (NOrig=A). This procedure you can help:

create or replace procedure amstrong_number(pNumber int)
is

  NOrig int:=0;
  N int:=0;
  R int:=0;
  R1 int:=0;
  A int:=0;

begin

  NOrig:=pNumber;
  N:=pNumber;

  WHILE N!= 0
  LOOP

    R:=MOD(N,10);
    R1:=POWER(R,3);
    A:=A+R1;
    N:=TRUNC(N/10);

  END LOOP;

  IF NOrig = A THEN
    dbms_output.put_line(' number is amstrong ');
  ELSE
    dbms_output.put_line(' number is not an amstrong ');
  END IF;

end;

Regards

Answer 2

In a comment you say you want to take user input from the keyboard. It is not clear how you plan to do that; in general, PL/SQL does not have facilities for interaction with end users, it is a language for processing on the server.

One way to have the user provide a number is to have a procedure with an in parameter. Below is one example of how you can do it. You must compile the procedure first (for example, I saved it in a script, "Armstrong.sql", and then I ran the command "start Armstrong" in SQL*Plus). Then the user can use the procedure, which I called is_Armstrong, from SQL*Plus or a graphical interface like SQL Developer or Toad, like this: exec is_Armstrong(...) where in parentheses is the user's input number.

I built in two application exception checks - for negative or non-integer numbers and for numbers that are too long (more than 20 digits). I wrote it for Armstrong numbers of arbitrary length (<= 20), limiting it to three digits doesn't save almost any work so why not make it general. There are other possible application exceptions - for example, what if the user inputs a string instead of a number? I didn't handle all the errors - the very last example below shows an unhandled one. Write your own error handling code for whatever else you want to handle explicitly.

Content of Armstrong.sql:

create or replace procedure is_Armstrong(p_input_number number)
as
   l_string varchar2(20);
   l_sum number := 0;
   l_loop_counter number;
   l_len number;
   not_a_positive_integer exception;
   number_too_large exception;
begin
   l_string := to_char(p_input_number); 
   l_len    := length(l_string);    
   if p_input_number <= 0 or p_input_number != floor(p_input_number) then
      raise not_a_positive_integer;
   elsif l_len > 20 then
      raise number_too_large;
   end if;
   for l_loop_counter in 1..l_len
   loop
      l_sum := l_sum + power(to_number(substr(l_string, l_loop_counter, 1)), l_len);
   end loop;
   if p_input_number = l_sum then
      dbms_output.put_line('Number ' || l_string || ' is an Armstrong number.');
   else 
      dbms_output.put_line('Number ' || l_string || ' is not an Armstrong number.');
   end if;
exception
   when not_a_positive_integer then
      dbms_output.put_line('Input number must be a positive integer.');
   when number_too_large then
      dbms_output.put_line('Input number must be no more than twenty digits.');
end;
/

Compiling the procedure:

SQL> start Armstrong.sql
Procedure created.
Elapsed: 00:00:00.03

Usage examples:

SQL> exec is_Armstrong(-33);
Input number must be a positive integer
PL/SQL procedure successfully completed.
Elapsed: 00:00:00.08

SQL> exec is_Armstrong(1.5);
Input number must be a positive integer
PL/SQL procedure successfully completed.
Elapsed: 00:00:00.08

SQL> exec is_Armstrong(1234512345123451234512345);
Input number must be no more than twenty digits
PL/SQL procedure successfully completed.
Elapsed: 00:00:00.01

SQL> exec is_Armstrong(3);
Number 3 is an Armstrong number.
PL/SQL procedure successfully completed.
Elapsed: 00:00:00.00

SQL> exec is_Armstrong(100);
Number 100 is not an Armstrong number.
PL/SQL procedure successfully completed.
Elapsed: 00:00:00.00

SQL> exec is_Armstrong(371);
Number 371 is an Armstrong number.
PL/SQL procedure successfully completed.
Elapsed: 00:00:00.00

SQL> exec is_Armstrong('abc')
BEGIN is_Armstrong('abc'); END;
*
ERROR at line 1:
ORA-06502: PL/SQL: numeric or value error: character to number conversion error
ORA-06512: at line 1
Elapsed: 00:00:00.00