Re: Signed Integer
"So you can represent dates before 1970"
Not really, as many time_t related stuff uses -1 to indicate an error.
You have to remember that the likes of time_t was created for the computer's sense of linear time (for more general uses where date/time format was commonly used) so UNIX creators cared not about pre-1970 and 1970 was therefore as good an epoch as any since 32-bits (or 31 really) put the range so far in the future that no one cared. Similarly DOS time and FAT file systems don't do pre-1980.