RE: How to do RPG-type I/O in Cobol

[Dan <dbcerpg@xxxxxxxxx>]

Hi Richard,

Thanks so much for your response!  I have the Cobol softcopy and I see
the references to some of the items I'm asking about, but I'm trying to
get an understanding of how the RPG & Cobol techniques compare, and
that's not real clear in the manual.  For example, as I explain below,
it appears that Cobol has no equivalent of RPG's READE.

When a READ is done, without NEXT, does it automatically use the key
defined in the RECORD KEY phrase of the file's SELECT group?  I noticed
the KEY IS phrase in the syntax diagram, but the example I provided
does not use it.  Is KEY IS sort of an override to use a different key
than the one specified in the SELECT?

In the START example:  When is it an INVALID KEY?  If there are no
records with a key that are "not less than" (sheesh, this should be
"greater than or equal to", yes?) the key defined?

Are the following statements correct:
1) READ without NEXT uses the key to do an RPG-type CHAIN; if a record
having the specified key does not exist, no record is returned to the
program.

2) READ NEXT always reads the record following the current record,
regardless of the key.  I interpret that to mean that a READ NEXT is
strictly an RPG-type READ (and not READE).  The lack of the INVALID KEY
phrase in the example seems to confirm this.

Thanks again!
- Dan

--- Richard Casey <casey_r@popmail.firn.edu> wrote:
> Hi Dan,
>
> You should be able to track down a COBOL reference manual at the
> InfoCenter.
> Check out
> http://publib.boulder.ibm.com/cgi-bin/bookmgr/DOCNUM/SC09-1813-00
>
> I know enough RPG to be dangerous (?!) so bear with me.
>
> The PCPESTCCP-READ paragraph is a random read (similar to RPG's
> CHAIN). I'm
> assuming that the file is defined as ACCESS DYNAMIC in the
> FILE-CONTROL
> section. ACCESS DYNAMIC allows you to do both sequential and random
> processing against a file.
>
> The PCPESTCCP-READ-NEXT paragraph is a sequential read (similar to
> RPG's
> READE). If I read the RPG manual correctly, READE allows you to
> specify a
> search argument that controls if READE returns a record to you or
> not.
> COBOL's READ NEXT is a little different in that it will return the
> next
> record regardless of the key (unless you hit end of file). You would
> then
> need to check the record to see if met your criteria.
>
> The PCPESTCCP-START-NOTLESS paragraph positions the file at the first
> record
> where the key is not less (i.e. >=) the specified value. This matches
> up
> with RPG's SETLL.
>
> Hope this helps! Holler if you need more info.
>
> Richard Casey

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