ABAP simple Calculator

*&---------------------------------------------------------------------*
*& Report  ZBC400_12_COMPUFIX
*&
*&---------------------------------------------------------------------*
*&
*&
*&---------------------------------------------------------------------*

REPORT zbc400_12_sub.

TYPES gty_result TYPE p LENGTH 16 DECIMALS 2.

PARAMETERS: pa_op TYPE c,
            pa_int1 TYPE i,
            pa_int2 TYPE i.

DATA gv_result TYPE gty_result.


IF ( NOT ( ( pa_op = '+' ) OR ( pa_op = '-' ) OR ( pa_op = '*' ) OR ( pa_op = '/' ) OR ( pa_op = '%' ) ) ) .
  WRITE 'Überprüfe die Eingabe, Trottel'.
ELSEIF ( ( pa_op = '/' ) AND ( pa_int2 = 0 ) ) .
  WRITE 'Keine Division durch Null, Troll'.
ELSE.
  CASE pa_op.
    WHEN '+'.
      gv_result = pa_int1 + pa_int2.
    WHEN '-' .
      gv_result = pa_int1 - pa_int2.
    WHEN '*' .
      gv_result = pa_int1 * pa_int2.
    WHEN '/' .
      gv_result = pa_int1 / pa_int2.

    WHEN '%' .
      PERFORM calc_percentage
        USING
          pa_int1
          pa_int2
        CHANGING
          gv_result.

  ENDCASE.
  WRITE: gv_result.
ENDIF.
*&---------------------------------------------------------------------*
*&      Form  CALC_PERCENTAGE
*&---------------------------------------------------------------------*
*       text
*----------------------------------------------------------------------*
*  -->  p1        text
*  <--  p2        text
*----------------------------------------------------------------------*
FORM calc_percentage  USING     pv_act TYPE i
                                pv_max TYPE i
                      CHANGING  cv_result.
  IF pv_max = 0.
    cv_result = 0.
    WRITE 'Fehler bei der Prozentrechnung :/'.
  ELSE.
    cv_result = pv_act / pv_max * 100 .
  ENDIF.
ENDFORM.                    " CALC_PERCENTAGE