topic what is the difference between using and changing? in Application Development and Automation Discussions

what is the difference between using and changing?

Former Member — Mon, 25 Feb 2013 07:02:37 GMT

Hi,

I have a confusion in using and changing, both works same.

then what is the difference in it .

please explain in simple way.

Regards

Arif

Moderator message : Search for available information, discussion locked.

Message was edited by: Vinod Kumar

Re: what is the difference between using and changing?

Former Member — Mon, 25 Feb 2013 07:06:48 GMT

Hello,

This is very basic question......do some research before posting at SCN.

using means -> call by reference.

changing means -> call by reference.

using value( ) means -> call by value...

changing value( ) means -> call by value and result..

Reg

Sabyasachi

Re: what is the difference between using and changing?

Former Member — Mon, 25 Feb 2013 07:25:46 GMT

Hi,

I know call by reference and call by value,

But question is differece between using and changing.

at the time of perfom.

perform xyz using p.

form using p1.

endform.

perform xyz changing p.

form changin p1.

endform.

both works same than what is difference in it.

Re: what is the difference between using and changing?

RaymondGiuseppi — Mon, 25 Feb 2013 07:32:34 GMT

As written in the documentation (Press F1 or read PERFORM - parameter_list) there is no difference between the two options, the CHANGING is only useful for maintenability of the program as it documents the interface - Read the Rules of Engagement before posting.

Regards,

Raymond

Re: what is the difference between using and changing?

Former Member — Mon, 25 Feb 2013 07:43:18 GMT

Hello mohd,

There is actually no difference between two options.......both are call by reference....... means same memory address......

Reg

Sabyasachi

Re: what is the difference between using and changing?

former_member183073 — Mon, 25 Feb 2013 07:48:08 GMT

Hi,

Major difference can be seen when you are using the addition using value(a) or changing value(a).

using value(a)--> it will pass the values in actual parameter to formal parameter and if you chang the value of 'a' in subroutine the value of actual parameter remains same as before passing.

Changing value(a)--> it will pass the values in actual parameter to formal parameter and if you change the value of a in subroutine the value of actual parameter changes as in formal parameter.

Re: what is the difference between using and changing?

Former Member — Mon, 25 Feb 2013 07:51:27 GMT

Hi Mohd,

Taking your example as below, when we define a variable as using, we can only use this to do operations within the sub-routine but can't actually change the value of this using parameter (its not advisable). When we define a variable as changing, we can actually change the value of that parameter. So that is actually the difference. Hope this helps or let me know if you have any doubts.

perform xyz using p.

form using p1.

endform.

perform xyz changing p.

form changin p1.

endform.

Re: what is the difference between using and changing?

Former Member — Mon, 25 Feb 2013 08:14:07 GMT

Hi,

There is a very basic difference between using and changing.

If we use using keyword with a subroutine then we can simply pass the value/reference to subroutine for processing but it will not reply back the changes done to the variable to the main program

If we have used changing keyword with subroutine then we can get back the changed value of the variable from the subroutine to the main program means whatever value changes occurred in subroutine will be reflected in main program

For Example.

data x TYPE i VALUE 10.

DATA y TYPE i VALUE 10.

PERFORM zsubusing1 USING x y .

WRITE: /' Value of X In Using = ',

PERFORM zsubchanging1 USING y CHANGING x .

WRITE: / ' Value of X after Changing = ',

*&---------------------------------------------------------------------*

*& Form ZSUBUSING1

*&---------------------------------------------------------------------*

* text

*----------------------------------------------------------------------*

* -->P_X text

* -->P_Y text

*----------------------------------------------------------------------*

FORM ZSUBUSING1 USING P_X

P_Y.

p_y = p_x + p_y.

ENDFORM. " ZSUBUSING1

*&---------------------------------------------------------------------*

*& Form ZSUBCHANGING1

*&---------------------------------------------------------------------*

* text

*----------------------------------------------------------------------*

* -->P_Y text

* <--P_X text

*----------------------------------------------------------------------*

FORM ZSUBCHANGING1 USING P_Y

CHANGING P_X.

p_x = p_x + p_y.

ENDFORM. " ZSUBCHANGING1

Re: what is the difference between using and changing?

Former Member — Mon, 25 Feb 2013 08:59:02 GMT

Hello,

Pass by reference for USING parameters

For the formal parameters p1 p2 ..., no local data object is created in the subroutine. Instead, when it is called, a reference is passed to the specified actual parameter. A change to the formal parameter in the subroutine also changes the value of the actual parameter.

Pass by reference for CHANGING parameters

The formal parameters p1 p2 ... are handled exactly like those parameters defined for pass by reference using USING.

Pass by value for USING parameters

For each formal parameter p1 p2 ..., a local object with the same data type as the corresponding actual parameter is created in the subroutine and filled with its values. A change to the formal parameter in the subroutine does not change the value of the actual parameter. The actual parameter also retains its original value even after the subroutine has ended.

Pass by value for CHANGING parameters

For each formal parameter p1 p2 ..., a local data object with the same data type as the corresponding actual parameter is created in the subroutine and filled with its values. A change to the formal parameter in the subroutine does not directly change the value of the actual parameter. If the subroutine is ended using <b>ENDFORM, RETURN, CHECK or EXIT</b> however, the content of the formal parameter is assigned to the actual parameter. If the subroutine is ended by a message or an exception, the actual parameter remains unchanged.

Thanks

Katrice