Date to Day-of-Week Conversion (Question)

[Mark Turner]

Hi folks! Can anyone help me with suggestions on how to convert a date to a
day of the week? For example, I start with a date like '19910619'; I'd like some
function to return 'Wed' or '4' or some such indication of the day. This must
be doable! 

One caveat: I'd rather not use a shell script (for instance, I could do this 
using cal and awk) - C would be best.

Please don't suggest that I should reset the system date and then pass a "tm" 
structure to the one of the ctime-related functions. I'd like to keep the 
machine up and running throughout the entire calculation!! :-)

Please mail and I'll post summaries if there is any interest (and the answer
*isn't* too embarassingly obvious).

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Mark Turner (markt at tse.UUCP), The Toronto Stock Exchange