> I'll never understand why they thought 0-based > months made sense, but then used 1-based days > and 1900-based years. Even if C did it[...] Java, Pe

> I'll never understand why they thought 0-based > months made sense, but then used 1-based days > and 1900-based years. Even if C did it[...] Java, Perl etc. all copied this pattern from localtime() in C. In all of these languages it's idiomatic to write something like: printf("%s %d, %d\n", mnames[mon], mday, year); To print out e.g. "January 6, 78". The reason month days aren't zero based is obvious, usually when you use them you aren't going to have go through a lookup table, whereas nobody calls January "0" or "1", so you'll always need a lookup table. Indexing months by 1 would mean declaring the "mnames" array would be the un-idoimatic: char *mname[] = { NULL, "Jan", ... }; Instead of: char *mname[] = { "Jan", ... }; Or you'd need to use the latter form and do lookups by mnames[mon - 1] instead of mnames[mon]. The reason you have to add 1900 to the year is that when C was made it was standard for software to use two-digit years, and if you told some of C's designers back in the 70s that we'd still be using & discussing these APIs in 2017 they'd probably have laughed at you. Of course sometimes you need to use month indexes themselves, e.g. if you wanted to print out 1978-01-06 in a log file: printf("%d-%d-%d...\n", year + 1900, mon + 1, mday, ...); But such are the trade-offs of low-level API design. I guess C's designers took the inherent idiomaticness of zero-based indexes & expectation that the common case would to print out month names over such use-cases.