Thursday, November 30, 2006

Hairiest Bug War Stories

I've seen a couple of bug-related items on the Net lately, and they reminded me of a piece in the April 1997 Communications of the ACM titled My hairiest bug war stories by Marc Eisenstadt. From this comes one of my favorite bug anecdotes about a program that only worked properly on Wednesdays:

"[Story B, excerpt] ...I once had a program that only worked properly on Wednesdays...The documentation claimed that the day of the week was returned in a doubleword, 8 bytes. In actual fact, Wednesday is 9 characters long, and the system routine actually expected 12 bytes of space to put the day of the week. Since I was supplying only 8 bytes, it was writing 4 bytes on top of storage area intended for another purpose. As it turned out, that space was where a "y" was supposed to be stored to compare to the users answer. Six days a week the system would wipe out the "y" with blanks, but on Wednesdays a "y" would be stored in its correct place. "

I found the entire original article online: here


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