cdate()
A standard *nix C library that one, not just Windows. I suspect MS "borrowed" it.
The only Y2K bug I actually saw in the wild on the 1st of January 2000[1] was due to the fact that variables cday, cmonth and cyear are available via inclusion of cdate.
cday is the numeric day of the month.
cmonth is the numeric month of the year.
cyear is, er, the number of years since 1900...........
The number of places sporting the date 1/1/100 was quite scary. My favourite find (once I'd worked out what was going on and told the C monkeys where the bug was in their sodding report headers) was the US Naval Observatory clock on the web........(!!)
[1] aka 2000-01-01. A day that I spent in the office watching nothing go wrong. Seriously, 1/1/100 was the highlight of the day.