ABAP pgm using append, sum, modify

Question

I am new to ABAP programming. Can somebody please help me out with the following program or give me some hints as to how to proceed?
1. ABAP inputs: The pgm will have following parameters:
   P_ITEM - input string of 20 characters (select options)
   P_QTY - input number (select options)
   P_RATE - input number with 2 decimal points (select options) 
2. Main processing logic:
   1. Accept 5 items each with qty and rate.
   2. store in internal table.
   3. calculate their price.
   4. sort on price in ascending order.
   5. display o/p as per section 3.
3. Output format:
   ITEM     QTY     RATE     PRICE
   TOTAL
Hints: For this ABAP make use of APPEND, SUM, MODIFY
Thank you.

Answer 1

This can be coded, but it does make much sense.  There is no "tie" between the selection-screen fields.  If you are assuming that the first value in P_ITEM corresponds to the first value in P_QTY and P_RATE, then you can do it, but this is not really a good way of coding.  Here is a sample anyway. 
Add values to all three select-options and hit execute.
report zrich_0004
       no standard page heading.
data: begin of itab occurs 0,
      item(20) type c,
      qty type i,
      rate type p decimals 2,
      price type p decimals 2,
      end of itab.
select-options: s_item for itab-item,
                s_qty  for itab-qty,
                s_rate for itab-rate.
start-of-selection.
  clear itab. refresh itab.
  loop at s_item.
    clear itab.
    itab-item = s_item-low.
    read table s_qty index sy-tabix.
    if sy-subrc = 0.
      itab-qty = s_qty-low.
    endif.
    read table s_rate index sy-tabix.
    if sy-subrc = 0.
      itab-rate = s_rate-low.
    endif.
    itab-price = itab-qty * itab-rate.
    append itab.
  endloop.
  sort itab ascending by price.
  loop at itab.
    write:/ itab-item, itab-qty, itab-rate, itab-price.
  endloop.
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Regards,
Rich Heilman