Re: Passed by Reference vs. Passed by Value

This is a comment not specifically to Dave's post but also to the post he was commenting on.

Programs can ONLY receive parameters by reference. The VALUE keyword is not permitted on a PI/PR for a program. If a parm is declared as CONST then IF it does not match the definition a copy is made and a pointer to the copy is passed. In all other cases a pointer to the original data is passed.

For procedures parms can be passed by reference or value. In both cases the parameters are effectively pushed onto the stack and then popped in the called procedure. If you pass a field by value a copy of the actual data is pushed on the stack. There are minor exceptions to this in a few oddball cases such as floating point fields but it is valid to think it this way.

On Mar 11, 2020, at 5:02 PM, dlclark@xxxxxxxxxxxxxxxx wrote:

"RPG400-L" <rpg400-l-bounces@xxxxxxxxxxxxxxxxxx> wrote on 03/11/2020
04:38:34 PM:

In which case, the variabkle is copied to a new location and *pointer to

new location* is passed to procedure.

In the end, you always passed a pointer under covert....

I used to think that. But then I ran into the situation where one
program was passing a parameter by reference (by default) but the called
program expected the parameter to be passed by value (explicitly) and the
called program couldn't see the passed value at all. Explain to me why is
that? Thanks for the education.


Sincerely,

Dave Clark
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