Y2K problem will come back again in 2038

19-January-2038 will suddenly become 13-December-1901

Note: This is just for FYI only, Please Don't try this. This is true and if you do this then your network based applications will not work.

The Year 2038 Problem

Test it now..... STEPS:

1. login to yahoo messenger

2. send instant message to anyone - fine its working...

3. now, change ur system date to 19-Jan-2038, 03:14:07 AM or above

4. Confirm weather ur date is changed

5. again send instant message to anyone...

Your YM crahes....



What is it?

Starting at GMT 03:14:07, Tuesday, January 19, 2038, It is expected to see lots of systems around the world breaking magnificently: satellites falling out of orbit, massive power outages (like the 2003 North American blackout), hospital life support system failures, phone system interruptions, banking errors, etc. One second after this critical second, many of these systems will have wildly inaccurate date settings, producing all kinds of unpredictable consequences. In short, many of the dire predictions for the year 2000 are much more likely to actually occur in the year

In the first month of the year 2038 C.E. many computers will encounter a date-related bug in their operating systems and/or in the applications they run. This can result in incorrect and wildly inaccurate dates being reported by the operating system and/or applications. The effect of this bug is hard to predict, because many applications are not prepared for the resulting "skip" in reported time anywhere from 1901 to a "broken record" repeat of the reported time at the second the bug occurs. Also, may make some small adjustment to the actual time the bug expresses itself. This bug to cause serious problems on many platforms, especially Unix and Unix-like platforms, because these systems will "run out of time".

What causes it?

Time_t is a data type used by C and C++ programs to represent dates and times internally. (Windows programmers out there might also recognize it as the basis for the CTime and CTimeSpan classes in MFC.)
time_t is actually just an integer, a whole number, that counts the number of seconds since January 1, 1970 at 12:00 AM Greenwich Mean Time. A time_t value of 0 would be 12:00:00 AM (exactly midnight) 1-Jan-1970, a time_t value of 1 would be 12:00:01 AM (one second after midnight) 1-Jan-1970, etc.. some example times and their exact time_t representations:

Date & time time_t representation

1-Jan-1970, 12:00:00 AM GMT 0

1-Jan-1970, 12:01:00 AM GMT 60

1-Jan-1970, 01:00:00 AM GMT 3 600

2-Jan-1970, 12:00:00 AM GMT 86 400

1-Jan-1971, 12:00:00 AM GMT 31 536 000

1-Jan-1972, 12:00:00 AM GMT 63 072 000

1-Jan-2038, 12:00:00 AM GMT 2 145 916 800

19-Jan-2038, 03:14:07 AM GMT 2 147 483 647

By the year 2038, the time_t representation for the current time will be over 2 140 000 000. And that's the problem. A modern 32-bit computer stores a "signed integer" data type, such as time_t, in 32 bits. The first of these bits is used for the positive/negative sign of the integer, while the remaining 31 bits are used to store the number itself.

The highest number these 31 data bits can store works out to exactly 2 147 483 647. A time_t value of this exact number, 2 147 483 647, represents January 19, 2038, at 7 seconds past 3:14 AM Greenwich Mean Time. So, at 3:14:07 AM GMT on that fateful day, every time_t used in a 32-bit C or C++ program will reach its upper limit.

One second later, on 19-January-2038 at 3:14:08 AM GMT, disaster strikes. When a signed integer reaches its maximum value and then gets incremented, it wraps around to its lowest possible negative value.

This means a 32-bit signed integer, such as a time_t, set to its maximum value of 2 147 483 647 and then incremented by 1, will become -2 147 483 648.
Note that "-" sign at the beginning of this large number. A time_t value of -2 147 483 648 would represent December 13, 1901 at 8:45:52 PM GMT.

So, if all goes normally, 19-January-2038 will suddenly become 13-December-1901 in every time_t across the globe, and every date calculation based on this figure will go haywire. And it gets worse.

Most of the support functions that use the time_t data type cannot handle negative time_t values at all. They simply fail and return an error code.

What is the Year 2038 problem?

The Year 2000 problem is understood by most people these days because of the large amount of media attention it received.

Most programs written in the C programming language are relatively immune to the Y2K problem, but suffer instead from the Year 2038 problem. This problem arises because most C programs use a library of routines called the standard time library . This library establishes a standard 4-byte format for the storage of time values, and also provides a number of functions for converting, displaying and calculating time values.

The standard 4-byte format assumes that the beginning of time is January 1, 1970, at 12:00:00 a.m. This value is 0. Any time/date value is expressed as the number of seconds following that zero value. So the value 919642718 is 919,642,718 seconds past 12:00:00 a.m. on January 1, 1970, which is Sunday, February 21, 1999, at 16:18:38 Pacific time (U.S.). This is a convenient format because if you subtract any two values, what you get is a number of seconds that is the time difference between them. Then you can use other functions in the library to determine how many minutes/hours/days/months/years have passed between the two times.

If you have read How Bits and Bytes Work, you know that a signed 4-byte integer has a maximum value of 2,147,483,647, and this is where the Year 2038 problem comes from. The maximum value of time before it rolls over to a negative (and invalid) value is 2,147,483,647, which translates into January 19, 2038. On this date, any C programs that use the standard time library will start to have problems with date calculations.

This problem is somewhat easier to fix than the Y2K problem on mainframes, fortunately. Well-written programs can simply be recompiled with a new version of the library that uses, for example, 8-byte values for the storage format. This is possible because the library encapsulates the whole time activity with its own time types and functions (unlike most mainframe programs, which did not standardize their date formats or calculations). So the Year 2038 problem should not be nearly as hard to fix as the Y2K problem was.

An alert reader was kind enough to point out that IBM PC hardware suffers from the Year 2116 problem. For a PC, the beginning of time starts at January 1, 1980, and increments by seconds in an unsigned 32-bit integer in a manner similar to UNIX time. By 2116, the integer overflows.

Windows NT uses a 64-bit integer to track time. However, it uses 100 nanoseconds as its increment and the beginning of time is January 1, 1601, so NT suffers from the Year 2184 problem.

On this page, Apple states that the Mac is okay out to the year 29,940!

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