Understanding and Using PHP's strtotime() Function

The strtotime() function is a powerful and flexible PHP tool that converts human‑readable date and time formats into UNIX timestamps.

Basic Syntax

<code>strtotime(string $time, int $now = time()): int|false</code>

Here $time is the date/time string to be parsed, and $now is an optional base timestamp (default is the current time). The function returns an integer UNIX timestamp or false on failure.

Common Format Examples

Relative dates and times: you can use descriptors like "now", "tomorrow", "next week", etc. <code>strtotime("tomorrow") // returns the UNIX timestamp for tomorrow</code>

Absolute dates and times: specify exact dates and optional times. <code>strtotime("2023-10-31") // timestamp for the given date strtotime("2023-10-31 08:30:00") // timestamp for the given date and time</code>

Relative time intervals: describe a duration to add to the base time. <code>strtotime("+1 day") // timestamp one day later strtotime("+1 week 2 days 4 hours 30 minutes") // timestamp after the specified interval</code>

Special keywords: the function supports phrases like "last day of month" or "first day of next month". <code>strtotime("last day of month") // timestamp for the last day of the current month strtotime("first day of next month") // timestamp for the first day of the next month</code>

Note that strtotime() 's parsing ability is limited; it may not handle uncommon or malformed formats, so inputs should follow supported patterns.

The function also accepts additional parameters such as timezone settings or specific weekday specifications, which can further enhance its flexibility.

Conclusion

strtotime() is a very useful PHP function for converting readable date strings into UNIX timestamps, enabling easy date calculations, but users must be aware of its parsing limits and ensure proper input formats.