ABAP : Recursive customer address

 "Call with Recursive concept
             flag = '1'.
             "line1
             PERFORM concat_txt USING  <fs_kna1>-ANRED CHANGING flag.
             PERFORM concat_txt USING  <fs_adrc>-name1 CHANGING flag.
             PERFORM concat_txt USING  <fs_adrc>-name2 CHANGING flag.
             "line2
             PERFORM concat_txt USING  <fs_adrc>-str_suppl1 CHANGING flag.
             PERFORM concat_txt USING  <fs_adrc>-roomnumber CHANGING flag.
             PERFORM concat_txt USING  <fs_adrc>-name_co    CHANGING flag.
             PERFORM concat_txt USING  <fs_adrc>-house_num1 CHANGING flag.
             PERFORM concat_txt USING  <fs_adrc>-str_suppl2 CHANGING flag.
             PERFORM concat_txt USING  <fs_adrc>-street     CHANGING flag.
             "Line3
             PERFORM concat_txt USING  <fs_adrc>-location   CHANGING flag.
             PERFORM concat_txt USING  <fs_adrc>-city2      CHANGING flag.
             PERFORM concat_txt USING  <fs_adrc>-city1      CHANGING flag.
             PERFORM concat_txt USING  <fs_adrc>-post_code1 CHANGING flag.

============================================================================
FORM concat_txt  USING    p_word
                 CHANGING p_flag.
  DATA : lv_string TYPE i,
         lv_sum_len    TYPE i,
         lv_word    TYPE i.

"This perform build with concept recursieve function

  CASE p_flag.
    WHEN '1'.
      lv_sum_len = strlen( p_word ) +  strlen( gs_header-line1 ).
      IF lv_sum_len >= 60.
         "do nothing but send to FORM concat_text
         p_flag = 2.
         PERFORM concat_txt USING p_word CHANGING p_flag.
      ELSE.
         CONCATENATE gs_header-line1 p_word INTO gs_header-line1 SEPARATED BY space.
      ENDIF.

    WHEN '2'.
      lv_sum_len = strlen( p_word ) +  strlen( gs_header-line2 ).
      IF lv_sum_len >= 60.
         "do nothing but send to FORM concat_text
         p_flag = 3.
         PERFORM concat_txt USING p_word CHANGING p_flag.
      ELSE.
         CONCATENATE gs_header-line2 p_word INTO gs_header-line2 SEPARATED BY space.
      ENDIF.

    WHEN '3'.
      lv_sum_len = strlen( p_word ) +  strlen( gs_header-line3 ).
      IF lv_word > 20 AND lv_string > 40.
         "do nothing but send to FORM concat_text
         p_flag = 4.
         PERFORM concat_txt USING p_word CHANGING p_flag.
      ELSE.
         CONCATENATE gs_header-line3 p_word INTO gs_header-line3 SEPARATED BY space.
      ENDIF.

    WHEN '4'.
      CONCATENATE gs_header-line4 p_word INTO gs_header-line4 SEPARATED BY space.
  ENDCASE.

ENDFORM.