Re: SFLNXTCHG head-scratcher

On Wed, May 13, 2015 at 11:44 AM, John R. Smith, Jr. <
smith5646midrange@xxxxxxxxx> wrote:

> This is correct.  You must do some type of I/O on the control record for
> the
> SFLNSTCHG to trigger.  It has been a long time but doing just a write
> instead of an EXFMT of the control record might work.
>
> -----Original Message-----
> From: RPG400-L [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On Behalf Of Roche,
> Bob
> Sent: Wednesday, May 13, 2015 12:40 PM
> To: RPG programming on the IBM i (AS/400 and iSeries)
> Subject: RE: SFLNXTCHG head-scratcher
>
> But the READC is already past that record so it won't read it again until
> you EXFMT(write/read) the subfile. At least I never got it to work without
> doing that.
>
>
>

A more complete description of get-next-changed operation (than what is
provided in RPG manual for READC op-code) is in Application Display
Programming manual:

http://www-01.ibm.com/support/knowledgecenter/ssw_ibm_i_61/rzahg/rzahgapdlprint.htm?lang=en

The interesting bit is that get-next-changed, following get-next-changed
that returns EOF, reads the first changed record.  No other I/O is required
for consecutive trips through the list of changed records.  Note that
get-next-changed turns off the changed indicator of the read record, so
update with SFLNXTCHG is required else after EOF there would be no changed
records.