Sequential file EOF

[Neil C]

Hi all,
is it possable to check for an EOF condition on an input file?

I have a simple job that reads a sequential file and writes another, after various lookups. I would like to be able to write to a third file, to record input and output record counts, and the value of various stage variables if required, and to do this AFTER an EOF condition on the input file.

I can arrange for there to be a special end of file record written to the input file, but I would have thought that I could test for the EOF condition.

I have seached this site, and the DS help files, to no avail.

Cheers,
Neil Courtney

[kcbland]

Have you considered sending output to an aggregator stage of your various metrics (row counts, etc)? Then output the aggregator data to another sequential file to have your metrics.

I've done job designs where a "ready" type file is created after the job is finished writing the main file. I stream to an aggregator the current date, as well as a literal "1". The aggregator groups by the date, and sums the "1" column. When the job finishes reading the source file, the aggregator will output its data to another sequential file. The result is a data file and a ready file that contains the date of the data and the row count. This is one method you might use.

[ray.wurlod]

If you're doing this in BASIC there's an easy answer. The ReadSeq statement takes its ELSE path if you are at end of file.

So you could:

Code: Select all

Loop
   ReadSeq Line From SeqFileVar Else Exit
   statements
Repeat

This can also be written using the Boolean context of ReadSeq.

Code: Select all

Loop
While ReadSeq Line From SeqFileVar
   statements
Repeat

You can also use the Seek statement in BASIC to position to end of file. This would be much more efficient if you weren't reading anyway.

Code: Select all

Seek SeqFileVar,0,2
Else
   * statements to handle Seek failure (corrupted file)
End

The 0 is an offset, the 2 means "from end of file". You can also position to an offset with respect to beginning of file or to current position.

Both of these statements are described in the BASIC manual, and are available at your release (4.x).