abap calc and first program

*&---------------------------------------------------------------------*
*& Report  Z_NAAME
*&
*&--------------  WRITE 'Hello world!'.---------------------------------*
*&                PARAMETERS: pa_name TYPE string.
*&                NEW-LINE.
*&----------------WRITE: 'Hello', pa_name.-----------------*

REPORT Z_NAAME.

PARAMETERS: pa_int1 TYPE i,
pa_int2 TYPE i,
pa_op TYPE c LENGTH 1 .

DATA gv_result TYPE p LENGTH 16 DECIMALS 2  .

IF ( pa_op = '+' OR
  pa_op = '-' OR
  pa_op = '*' OR
  pa_op = '/' AND pa_int2 <> 0 ).

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.
ENDCASE.
 " -,
  "*,
  "/ .

WRITE: 'Result: ', gv_result .

ELSEIF pa_op = '/' AND pa_int2 = 0.
  WRITE 'no division by zero' .
ELSE.

ENDIF .