Retrieving the union of letters from two or more character strings

Question

Dear Gurus,
Need your help in writing ABAP logic for the below requirement.
Assume we have Var1 = 'ABCD' , Var2 = 'CDEF' and Var3 = 'EFGH'. The requirement is to populate Var4 with union of the letters from the above three strings. That means, Var4 should be equivalent to 'ABCDEFGH' after the logic is executed. Can any body help in writing this logic.
Appreciate your quick help.
Thanks
Aryan

Answer 1

Here's an algorithm that might work for you.. I'm sure there are plenty more!
report zlocal_jc_union.
parameters:
  p_var1(10)            type c default 'ABCD',
  p_var2(10)            type c default 'CDEF',
  p_var3(10)            type c default 'EFGH'.
start-of-selection.
  perform logic.
*&      Form  logic
form logic.
* "Work out unique letters and keep them in sequence.
  data:
    l_union(300)        type c,
    l_byte(1)           type c,
    l_offset            type i.
  concatenate
    p_var1
    p_var2
    p_var3 into l_union. "append them together
  format reset.
  write: / 'Before:', l_union(80).
*" then remove duplicates, one at a time...
  do.
    l_byte = l_union+l_offset(1).
    do.
      replace l_byte with space into l_union.
      if not sy-subrc is initial. "no more to replace
        exit.
      endif.
    enddo.
    l_union+l_offset(1) = l_byte. "replace original value
    condense l_union no-gaps.
    write: / 'Offset', l_offset, l_union(80).
    add 1 to l_offset.
    if l_offset = strlen( l_union ). "run out of bytes
      exit.
    endif.
  enddo.
endform.                    "logic