RE: Unix API read()

["Richard Jackson" <richardjackson@xxxxxxxxxxxxxxxxxx>]

I think that strtok wants a delimiter list containing blank, comma,
parenthesis, and so forth.  Parsing a database record where a character
column might contain any or all of those delimiters or no delimiters at all
might be unreliable.

When I made my suggestion, I was assuming that the string fields were
null-terminated and that other data types were recognizable within the rules
of fscanf.

If the columns don't meet that specification then Phil will have to do all
the work himself using arrays and so forth.  I suggest that functions be
created to read each data type and that the mainline should be coded to pick
out the fields in order.  Something like this:

* read record from file
GetRecord();
* extract fields
next = 0;
next = GetIntField(next,addr(field1),4,0); /* get an int field 4 bytes long
*/
next = GetCharField(next,addr(field2),10); /* get a char field */
...
* write out the new record
PutRecord();

In this case, GetIntField would accept a starting location, a pointer
specifying where to store the data, data length, and decimals.  It would
read the value from the input buffer, convert the value that it finds to the
defined output format spec, and write it to the output buffer location.  It
returns next, the input buffer byte offset for the byte one past the end of
the field that it just processed.  In other words, GetIntField tells
GetCharField where to start in the buffer.

This design has a couple of interesting characteristics.  First, it is
trivial to use the components in another program that extracts the data for
another file.  It is almost trivial to write a generator that uses a DSPFFD
outfile.  It is a little more complex to write a general purpose program to
read data from any file using a DSPFFD outfile as input and write any other
file containing columns in a different order or a subset of rows or columns.

I wish that I had retained all the versions of this that I have ever
written.  I used the first one in a softcoded EDI translator in the middle
'80s.  It was written in RPG for the System 38.  The second one went into a
generic file copy routine - stream files to AS/400 database files and the
other way 'round.  This version was written in C for either the PC or
AS/400.  I seem to recall a version in PL/I in the early 90s but I don't
remember what it was for.

I hope that you can use either fscanf or strtok.  If not, build good
architecture and test thoroughly.

Richard Jackson

-----Original Message-----
From: owner-rpg400-l@midrange.com [mailto:owner-rpg400-l@midrange.com]On
Behalf Of Anton Gombkötö
Sent: Thursday, December 28, 2000 3:52 AM
To: RPG400-L@midrange.com
Subject: RE: Unix API read()


At 18:14 27.12.00 -0800, you wrote:
>Richard,
>
>This looks good.  Can I call this from an rpg pgm?  It
>isn't one of the UNIX-like api's.  The 400 I'm using
>doesn't have a c compiler.  Without that I don't know
>if I can some how prototype it.

You do not need a C-compiler to use "C"-functions.

You'll find valuable information here:

redbook "Who knew you could do that with RPG?":
http://www.redbooks.ibm.com/abstracts/sg245402.html

Maybe you'll find the strtok example interesting...
A savf with the examples is available by clicking on "additional material".



Mit freundlichen Grüssen / best regards

Anton Gombkötö

Avenum Technologie GmbH
Wien - Mattsee - Stuttgart
e-mail Office   :       mailto:Anton.Gombkoetoe@avenum.com
Homepage        :       http://www.avenum.com

Lest das Redbook / read the redbook "Who knew you could do that with RPG?":
http://www.redbooks.ibm.com/abstracts/sg245402.html

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