Exporting, Importing and Changing values in ABAP Objects with example

*&---------------------------------------------------------------------*
*& Report Z_08
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*&---------------------------------------------------------------------*
*&
*&
*&---------------------------------------------------------------------*

REPORT ZKRISH_OOPS_08.

DATA W_TAX TYPE P DECIMALS 2.
DATA W_SAL TYPE P DECIMALS 2.

*----------------------------------------------------------------------*
* CLASS c1 DEFINITION
*----------------------------------------------------------------------*
CLASS TAX DEFINITION.
PUBLIC SECTION.
METHODS: TAX_CALC IMPORTING GRADE TYPE C
EXPORTING ITAX TYPE P
CHANGING SAL TYPE P.
ENDCLASS. "c1 DEFINITION
.
*----------------------------------------------------------------------*
* CLASS c1 IMPLEMENTATION
*----------------------------------------------------------------------*
CLASS TAX IMPLEMENTATION.
METHOD: TAX_CALC.
CASE GRADE.
WHEN 'A'.
ITAX = SAL * '0.3'.
WHEN 'B'.
ITAX = SAL * '0.2'.
WHEN 'C'.
ITAX = SAL * '0.1'.
ENDCASE.
SAL = SAL - ITAX.
ENDMETHOD. "tax_calc
ENDCLASS. "tax IMPLEMENTATION

START-OF-SELECTION.
DATA: O1 TYPE REF TO TAX.
CREATE OBJECT O1.


W_SAL = 30000.
WRITE: / W_SAL, W_TAX.

CALL METHOD O1->TAX_CALC
EXPORTING
GRADE = 'B'
IMPORTING
ITAX = W_TAX
CHANGING
SAL = W_SAL.
WRITE: / W_SAL, W_TAX.