Re: [C400-L] Returning parms from a C program to a CL program.

[Simon Coulter <shc@xxxxxxxxxxxxxxxxx>]

On 02/10/2004, at 12:48 PM, Hall, Philip wrote:

> Perhaps he aimed it towards the Jabberwocky reference.

Maybe so, its a neat poem. The Alice books and Pooh Bear books are 
among my favourites--even now.

> Or maybe to the fact that the code he quoted was stuffing (what could 
> be potentially) a large amount of data into argv[1] with no regard to 
> the size of the allocated memory being used by argv[1].

True, I did state that parameters in the caller and callee must be 
compatible.  That's no different from parameter mismatches in any 
programming language. For example:

PGMA:
D parm1       S       10
C              CALL     PGMB( parm1 )

PGMB:
D pgmb       PI
D parm1              100
C            EVAL    parm1 = *ALL'X'

Oops, just trashed caller's storage.

The caller could provide the available length in another argument. The 
callee could use strlen(argv[1]) to derive a possible maximum length, 
presuming the caller blank-filled and null-terminated the input string, 
or could use the CEEDOD API to determine the data type and length.

> Or maybe to the suggestion that the same method could be used for 
> returning packed decimal data too.

It can be, although I prefer the casting alternative.

I guess I'm curious as to why an OS/400 C programmer would think doing 
these things is strange. I can certainly understand why C weenies from 
other platforms would think this strange but OS/400 programmers should 
be familiar with pass-by-reference dynamic program calls.

Regards,
Simon Coulter.
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