#Php date format seconds since 1970 software#

This changes the integer value to −(2 31), or 2 31 seconds before epoch rather than after, which systems will interpret as 20:45:52 on Friday, 13 December 1901. Systems that attempt to increment this value by one more second to 2 31 seconds after epoch (03:14:08) will suffer integer overflow, inadvertently flipping the sign bit to indicate a negative number. Consequently, if a signed 32-bit integer is used to store Unix time, the latest time that can be stored is 2 31 − 1 (2,147,483,647) seconds after epoch, which is 03:14:07 on Tuesday, 19 January 2038. Thus, a signed 32-bit integer can only represent integer values from −(2 31) to 2 31 − 1 inclusive. Unix time has historically been encoded as a signed 32-bit integer, a data type composed of 32 binary digits (bits) which represent an integer value, with 'signed' meaning that the number can represent both positive and negative numbers, as well as zero and is usually stored in two's complement format. Unix time is defined as the number of seconds elapsed since 00:00:00 UTC on 1 January 1970 (an arbitrarily chosen time based on the creation of the first Unix system), which has been dubbed the Unix epoch. Many computer systems measure time and date as Unix time, an international standard for digital timekeeping. There is no universal solution to the problem, though many modern systems have been upgraded to measure Unix time with signed 64-bit integers which will not overflow for 292 billion years-approximately 21 times the estimated age of the universe. The most vulnerable systems are those which are infrequently or never updated, such as legacy and embedded systems. Some applications that use future dates have already encountered the bug. The problem is similar in nature to the year 2000 problem.Ĭomputer systems that use time for critical computations may encounter fatal errors if the Y2038 problem is not addressed. Attempting to increment to the following second (03:14:08) will cause the integer to overflow, setting its value to −(2 31) which systems will interpret as 2 31 seconds before epoch (20:45:52 UTC on 13 December 1901).

The data type is only capable of representing integers between −(2 31) and 2 31 − 1, meaning the latest time that can be properly encoded is 2 31 − 1 seconds after epoch (03:14:07 UTC on 19 January 2038).

The problem exists in systems which measure Unix time – the number of seconds elapsed since the Unix epoch (00:00:00 UTC on 1 January 1970) – and store it in a signed 32-bit integer. The year 2038 problem (also known as Y2038, Y2K38, Y2K38 superbug or the Epochalypse ) is a time formatting bug in computer systems with representing times after 03:14:07 UTC on 19 January 2038. The overflow error will occur at 03:14:08 UTC on 19 January 2038.

#Php date format seconds since 1970 software#

Computer software bug occurring in 2038 An animated visual of the bug in action.