5 ms·

The worst bug I encountered was due to IBM MVS (or COBOL--I was never sure which was at fault) losing addressability of part of a variable length record. Now yo

The worst bug I encountered was due to IBM MVS (or COBOL--I was never sure which was at fault) losing addressability of part of a variable length record. Now you see it, now you don't. The solution at our shop was to move the whole record to itself before attempting to look into the record. I was a newbie. If the old guard hadn't told me that workaround, I NEVER would have thought of it. This problem eventually went away, but 25 years later we still occasionally ask each other "did you try moving it to itself" when dealing with new problems. We chuckle, while today's newbies shake their heads at our Old Fart humor. The worst one I ever caused was when Visa started carrying two amount fields in their credit card records. One was the amount in original currency, the other was converted to the receiving system's local currency. I used the original amount. Our hand-made test data used the same currency for both amounts, so no problem in test. Imagine my surprise when we went live and our system started posting original currency amounts to cardholder accounts, which at the time only supported US dollars. Luckily, we caught it early and senior management and cardholders were all good sports about it. I think those credit card statements with massive amounts became collector's items.

dandrews 17y ago
Since you mention COBOL records were variable-length I'd guess that they probably contained ODOs (Occurs-Depending-On, variable length arrays for those of you who aren't COBOL literate). In order for a group or record MOVE to work properly you had to move the subordinate ODO values first, otherwise the runtime system would miscalculate the target record length, possibly truncating the MOVE. This also meant you couldn't use READ INTO for variable length records (which is equivalent to a READ followed by a MOVE) without taking some care. As you say: "newbies shake their heads..."

dandrews 17y ago

Since you mention COBOL records were variable-length I'd guess that they probably contained ODOs (Occurs-Depending-On, variable length arrays for those of you who aren't COBOL literate). In order for a group or record MOVE to work properly you had to move the subordinate ODO values first, otherwise the runtime system would miscalculate the target record length, possibly truncating the MOVE. This also meant you couldn't use READ INTO for variable length records (which is equivalent to a READ followed by a MOVE) without taking some care. As you say: "newbies shake their heads..."