Re: Returning parameters from C to CL

Thanx Simon and Elvis.
I understood the way to return results from C program to CL via argv[], the approach is absolutely clear to me and is not alien.
Just thought, that it COULD BE easier to use simply return(<something>), if this <something> could be available in CL.
QUSRJOBI cannot be named "an easier way" to retrieve return code, so I'll use argv[] rather...

That is odd, I should say.

-----Original Message-----
From:
c400-l-bounces+jevgeni.astanovski=sampopank.ee@xxxxxxxxxxxx
[mailto:c400-l-bounces+jevgeni.astanovski=sampopank.ee@midrang
e.com]On Behalf Of Simon Coulter
Sent: Friday, August 22, 2008 2:46 AM
To: C programming iSeries / AS400
Subject: Re: [C400-L] Returning parameters from C to CL



On 22/08/2008, at 12:07 AM, Jevgeni Astanovski wrote:

Tried to understand how to return value from a C program to a CL.
That is CL program calls C program and C program wants to return
value to it.

Need to clarify: Do you mean a "return value" from main (i.e. return
(1) ) or bi-directional parameters where your CL passes a variable to
C and you want C to change that variable value so that when the C
program ends the CL program can use the new value?

Actually C program is mine, so whatever value can be returned -
string or integer.
It must be treated by CL as boolean - YES or NO.
If I call C program with a one parameter variable from CL and then
modify this parameter in C, then the changed value will be
available in CL on return. Yes?

Yes. Alien concept to most C programmers because argv[] is
essentially input-only on other platforms. All you have to do is copy
the output value to the dereferenced argv[] element. Your C program
does need to KNOW the data type expected/passed by the caller and how
much space is allocated by the caller. In CL, RPG, and COBOL this
parameter matching is handled by the definition of the entry point.
In C you have to deal with it yourself.

But is there a way to receive the return() value?
That is if I complete my C program with return(172), then CL
somehow knows, that 172 is returned?

Ah, OK. This is possible but not as straight-forward as you might
hope. Refer to Page 298 in the V.4 C Programmer's Guide. You have to
call the QUSRJOBI API with format JOBI0600. Why IBM didn't just reuse
the RTNCODE parameter (or add a new one) on the RTVJOBA command is
beyond me (perhaps because RTNCODE is a decimal(5,0) and is too small
to hold all possible values returned from main).

Below is an extract from the manual (ILE/C programming guide, v.4,
p.265-266), it should be the thing I'm looking for
----------------------------------------------

<<< stuff deleted >>>

------------------------------------------------
But I cannot understand, where the command SQUARE calls C program
SQIFT and HOW it reads returned value.

The command calls SQIFT when it is run because SQIFT is named on the
PGM keyword of the CRTCMD command. CRTCMD converts command source
into a *CMD object and links it to the program (the command
processing program) specified on the PGM keyword.

I think the confusion here is caused by CL **command** and CL
**program**. You want to return a value from C to a CL **program**
but the example is using a CL **command**. The command processing
program is in C and is not returning a value from main. It is
receiving a value from the main() of a second C program SQ.

Sorry for my english, its not native. May be that's the problem :-(

Much better than me trying to communicate with you in your native
language!

Regards,
Simon Coulter.
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