AW: Prototype Definitions

Hi Mike,

OPTIONS(*NOPASS) means you'll pass a character field with a fixed length.
The compiler does not check if the length of the passed field is identical
to the expected field length. This gives you the ability to pass character
fields that are shorter as the maximum length defined in the prototype.
If neither the keyword CONST nor the keyword VALUE are specified for the
parameter, you have to check the incomming length of the parameter in your
called procedure. If less bytes as expected are passed, you only can change
the incomming bytes, otherwise you'll override global memory!! To determine
the incomming length you have to add the keyword OPDESC to the Prototype and
use the API CEEDOD in the called procedure.

Varying means a field with varying length is passed.
A varying length field has 2 preceeding bytes that contain the actual length
of the field.
Because the length is implicitely passed with the parameter field, no
additional actions are needed in the called procedure.
If it is an input/output parameter you can change the length of data,
without overriding memory. The new length is also stored in these 2
preceeding bytes.

Even if I said, "field passed" only a pointer to the parameter field is
passed to the called procedure, as long the keyword VALUE is not specified.

I hope this helps

Birgitta

-----Ursprungliche Nachricht-----
Von: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx]Im Auftrag von Mike Pantzopoulos -
(H/O)
Gesendet: Donnerstag, 6. Oktober 2005 03:57
An: RPG programming on the AS400 / iSeries
Betreff: RE: Prototype Definitions


Thanks.
It's been driving me crazy. They seem to be saying the same thing but
subtle differences are deadly in the arcane art of procedures. I'm sure
I'll be asking more before the end of today (In Australia).



-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of JK
Sent: Thursday, 6 October 2005 11:53 AM
To: 'RPG programming on the AS400 / iSeries'
Subject: RE: Prototype Definitions


Mike,

 The archives contain several excellent discussions on this. Search for
'varying varsize'. Omit the * preceding "*varying" and "*varsize"
because it just confuses the search engine.

http://archive.midrange.com/rpg400-l/

JK


> -----Original Message-----
> From: rpg400-l-bounces@xxxxxxxxxxxx
> [mailto:rpg400-l-bounces@xxxxxxxxxxxx]
> On Behalf Of Mike Pantzopoulos - (H/O)
> Sent: Wednesday, October 05, 2005 8:36 PM
> To: rpg400-l@xxxxxxxxxxxx
> Subject: Prototype Definitions
>
> Could some kind soul please describe the difference between the
> following prototype definitions:
>
> *VARYING
> OPTIONS(*VARSIZE)
>
> Thanks heaps.
>
> Mike Pantzopoulos

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