>From wiki: >There was originally some controversy over whether the Unix time_t should be >signed or unsigned. If unsigned, its range in the future would be doubled, >postponing the 32-bit overflow (by 68 years). However, it would then be >incapable of representing times prior to 1970. Dennis Ritchie, when asked >about this issue, said that he hadn't thought very deeply about it, but was of >the opinion that the ability to represent all times within his lifetime would >be nice. (Ritchie's birth, in 1941, is around Unix time −893 400 000.) >The consensus is for time_t to be signed, and this is the usual practice. The >software development platform for version 6 of the QNX operating system has an >unsigned 32-bit time_t, though older releases used a signed type.
>In some newer operating systems, time_t has been widened to 64 bits. In the >negative direction, this goes back more than twenty times the age of the >universe, and so suffices. In the positive direction, whether the >approximately 293 billion representable years is truly sufficient depends on >the ultimate fate of the universe, but it is certainly adequate for most >practical purposes. This is a good example when one wants to represent big numbers, he doesn't use usigned type, he uses signed 64-bit type.
