ABAP开发之引用传递和值传递

直接上代码：

REPORT  ZCALL.
DATA GV_NUM1 TYPE I VALUE  10.
DATA GV_NUM2 TYPE I VALUE  10.
WRITE:/ '引用调用前：',GV_NUM1,GV_NUM2.
PERFORM ADD_NUM_R USING GV_NUM1 CHANGING GV_NUM2.
WRITE:/ '引用调用后：',GV_NUM1,GV_NUM2.

WRITE:/ '值调用前：',GV_NUM1,GV_NUM2.
PERFORM ADD_NUM_V USING GV_NUM1 CHANGING GV_NUM2.
WRITE:/ '值调用后：',GV_NUM1,GV_NUM2.

*&---------------------------------------------------------------------*
*&      Form  ADD_NUM_R
*&---------------------------------------------------------------------*
*       text
*----------------------------------------------------------------------*
*  -->  p1        text
*  <--  p2        text
*----------------------------------------------------------------------*
FORM ADD_NUM_R  USING P_NUM1
                CHANGING P_NUM2 .
  P_NUM1 = P_NUM1 + 1.
  P_NUM2 = P_NUM2 + 1.
ENDFORM.                    " ADD_NUM
*&---------------------------------------------------------------------*
*&      Form  ADD_NUM_V
*&---------------------------------------------------------------------*
*       text
*----------------------------------------------------------------------*
*      -->p1  text
*      <--p2  text
*----------------------------------------------------------------------*
FORM ADD_NUM_V  USING VALUE(P_NUM1)
                CHANGING VALUE(P_NUM2).
  P_NUM1 = P_NUM1 + 1.
  P_NUM2 = P_NUM2 + 1.
ENDFORM.                    " ADD_NUM_V

执行结果：

从结果可以看出，引用传递时USING和CHANGING没什么区别，而值传递时CHANGING后的值会改变。