Re: Passing Parameter as Variable vs as address of variable

Hello Vern,

Am 26.08.2023 um 19:17 schrieb Vern Hamberg via RPG400-L <rpg400-l@xxxxxxxxxxxxxxxxxx>

I think you might be used to programming in C or C++ - in those languages, parameters are passed by value, by default. To pass by reference, you have to prefix the parameter name with an asterisk. As you know.

Thanks. Your assumption about my skill is correct. :-)

In IBM i languages, CL and RPG (I don't know about COBOL), the default is that parameters are passed by reference. This is automatic, unless you specify "by value".

I'm aware.

So it is extremely _*not*_ recommended to pass a pointer (by value). You completely lose any data type checking when compiling that program.

I was not aware that passing a pointer includes not only a bare "look at this address", but also some additional data. :-O

Also, you cannot define an RPGLE program to have an incoming parameter passed in by value - so all RPG (and CL) programs expect to receive a pointer to whatever parameter is listed. I just verified this, both with the default MAIN procedure that uses the cycle and with a MAIN control-option where you specify a procedure the does not use the cycle.

Thanks for taking time to run a test!

I think, the "conversion to a value" is merely a duplication of the data to a new memory location and *that* location is passed to the called application. Yes?

Performance-wise, as soon as data duplication happens, there is a (negligible?) performance penalty.

:wq! PoC