Deciphering UNIX Timestamps: A Comprehensive Exploration

A Unix timestamp: What is it?
To put it simply, time is tracked as a running total of seconds using the Unix timestamp. On January 1st, 1970 at UTC, the Unix Epoch marks the beginning of this count. Thus, all that remains of the Unix timestamp is the number of seconds that separate a given date from the Unix Epoch. It should be noted that, strictly speaking, this moment in time remains the same wherever you are in the world. Computer systems can utilize this to track and organize outdated data in dynamic, distributed applications that are client-side and online. Webmasters use Unix timestamps because they can simultaneously reflect all time zones.

What is the purpose of strtotime()?
The strtotime() function is used, as its name implies, to convert a date string to a Unix timestamp (str to time).

From [the strtotime() manual documentation in the PHP handbook] 2:

parse any English textual datetime description into a Unix timestamp using the strtotime function.

For instance, if you wanted to obtain the Unix timestamp for December 25, 2013, you would use strtotime() in the following manner:

echo strtotime(“25 December 2013”), “\n”; // => 1387909800 strtotime() is also capable of handling date and relative time formats. Consider the following, for instance:

echo strtotime(“+1 month”), “\n”; 1390980039
1391152839 is the result of echoing strtotime(“last day of next month”), “\n”.
These are a few simple instances. Very complicated date formats can also be handled via strtotime().

When is a timestamp appropriate to use?
No matter where it is calculated from or what time zone it is in, a Unix timestamp is always interpreted the same. Use a timestamp to get the date and time to reflect the preferences of individual users if your web service is used across several time zones.

The primary purpose of strtotime() is date format conversion. The date string is converted to a timestamp using strtotime(), which can parse practically any date string. You can use date() or other functions of a similar nature to format the timestamp once you have it.

strtotime()’s limitations
The largest integer value on a 32-bit machine is 2,147,483,647. Tuesday, January 19, 2038, at 03:14:07 UTC is the farthest time that may be expressed in this manner. This dilemma is sometimes referred to as Year 2038

Refer to the following PHP handbook note:
Generally, a timestamp’s valid range is Fri, Dec. 13, 1901, 20:45:54 UTC to Tue., Jan. 19, 2038, 03:14:07 UTC. (These are the dates for a 32-bit signed integer that represent its minimum and maximum values.) Furthermore, not all platforms allow negative timestamps, thus the earlier part of the Unix epoch may be the only date range you may choose from. This means that, for example, certain Linux distributions, Windows, and dates that fall before January 1, 1970,will incompatible with a few other operating systems, Windows, and some Linux distributions. However, PHP 5.1.0 and later versions get around this restriction.

Utilize DateTime entities.
DateTime objects in PHP can handle a much larger range of dates, so if your dates fall outside of the 13 Dec 1901 to 19 Jan 2038 range, you might want to give them a try. Approximately 293 billion years can be represented by DateTime in any way.

PHP versions higher than 5.2.0 can use the DateTime class. Utilizing DateTime is recommended when working with dates and times if you are using a PHP version higher than 5.2.0. It’s the most effective course of action. Update your PHP version right away if it’s outdated. Forgetful is anything older than 5.3.0.

A DateTime object can be created using DateTime::createFromFormat() or DateTime::__construct(). Keep in mind that PHP >= 5.3 is the only version on which DateTime::createFromFormat() works. You may parse strange date and time strings by using this technique.

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