Interesting Unix Time

by admin

If you set the preference of you system time, you will find a clock type called “UNIX time“.


If “UNIX time” is selected, what will happen?


Cool! This is the time here. Isn’t it interesting? Well, it may be confusing as hell, and you may ask what’s the time it is. Let’s investigate what’s Unix Time.

Unix time is displayed in seconds elapsed since January 1, 1970. It is stored in a 32-bits integer, time_t. So, it looks like this.

But there is a small issue there, say, as long as the largest integer a 31-bits(1 bit for sign bit) number can represent is 2^31 that is 2147483648. So large? What time it is? It is exactly 03:14:07am(GMT), January, 19th, 2038. This is the famous 2038 problem. After this time, the variable will turn into 10000000000000000000000000000000, which is -2147483648 in decimal. Is that tricky? What’s the time then? May be 8:45:52pm, December, 13rd, 1901. Wow, it’s really a big problem, almost all the computer will be crashed at that time. Is that true? Of course, but I don’t think that will be a critical problem, because after 30 years, almost all the computer will be upgraded in to 64-bits or even 128-bits(256-bits?). The problem will be easily fixed then. So, just think it as a tricky, rather a problem.

At last, I want to say, enjoy your Unix time! You know, developers are the primary users of it.

Not all 650-393 students are qualified for 642-446 or 642-503. They need to write 156-215 as well as 642-436 in order to prepare for 70-284.