How to do calculation to a variable in Sapscript form

Question

Hi experts,
My question looks simple but I failed to solve it. Supposed in the Sapscript form there are two variables: &it_tab-qty1&, &it_tab-qty2&. I need to add the first variable's value to the second one, I tried as below in Sapscript form editor:
/: &it_tab-qty2& = &it_tab-qty2& + &it_tab-qty1&
But it doesn't work. Could you please tell me the syntax to do such calculation in Sapscript? I cannot modify the print program so I have to modify the Sapscript form instead.
Thanks a lot.
Yu

Answer 1

Yes, you need to write an external program using SE38 to perform the calculation.
The syntax in SAPscript:
/* all the var define in the SAPscript is char string type
/: define &v1& = &it_tab-qty1&
/: define &v2& = &it_tab-qty2&
/: define &v3& = ''
/* GET_COMPNAME is the form name & Z001 is the program name
/: PERFORM GET_COMPNAME IN PROGRAM Z001
/: USING &v1&
/: USING &v2&
/: CHANGING &v3&
/: ENDPERFORM.
The syntax in program Z001 (Created by SE38):
REPORT ZFIR001.
FORM GET_COMPNAME tables in_tab structure itcsy
                                                 out_tab structure itcsy.
  data : p_1 TYPE CHAR80,
           p_1 TYPE CHAR80,
           p_3 TYPE CHAR80.
  retrieve data from the SAPscript
    READ table in_tab index 1.
    MOVE in_tab-value to p_1.
    READ table in_tab index 2.
    MOVE in_tab-value to p_1.
  Write the code to convert p_1 & p_2 to numeric and perform the addition to p_3
  After that convert the p_3 to char.
  send data back to the SAPscript
    read table out_tab index 1.
    move p_3 to out_tab-value.
    modify out_tab index sy-tabix.
ENDFORM.