解决负号后置问题

以下是一个简易计算器： 
DATA:
      V_RESULT type C length 8,
      V_METHOD TYPE C.
PARAMETERS:
  I_NUM1 TYPE I default 5,
  I_NUM2 type I default 10.
START-OF-SELECTION.
PARAMETERS:
  C_METHOD TYPE C DEFAULT '+'.
START-OF-SELECTION.
  V_METHOD = C_METHOD.
  IF V_METHOD = '+'.
  V_RESULT = I_NUM1 + I_NUM2.
  ENDIF.
 IF V_METHOD = '-'.
  V_RESULT = I_NUM1 - I_NUM2.
  ENDIF.
  IF V_METHOD = '*'.
  V_RESULT = I_NUM1 * I_NUM2.
  ENDIF.
  IF V_METHOD = '/'.
  V_RESULT = I_NUM1 / I_NUM2.
  ENDIF.
IF v_result le 0.
  v_result = v_result * -1.
  concatenate '-' v_result into v_result.
  condense v_result.
ENDIF.
end-of-selection.
  WRITE: / V_RESULT.