I can see great answers, so there's no need to repeat here, so I'd like to offer some advice:
I would recommend using a Unix Timestamp integer instead of a human-readable date format to handle time internally, then use PHP's date[] function to convert the timestamp value into a human-readable date format for user display. Here's a crude example of how it should be done:
// Get unix timestamp in seconds
$current_time = date[];
// Or if you need millisecond precision
// Get unix timestamp in milliseconds
$current_time = microtime[true];
Then use $current_time as needed in your app [store, add or subtract, etc], then when
you need to display the date value it to your users, you can use date[] to specify your desired date format:
// Display a human-readable date format
echo date['d-m-Y', $current_time];
This way you'll avoid much headache dealing with date formats, conversions and timezones, as your dates will be in a standardized format [Unix Timestamp] that is compact, timezone-independent [always in UTC] and widely supported in programming languages and databases.
[PHP 4, PHP 5, PHP 7, PHP 8]
date — Format a Unix timestamp
Description
date[string $format, ?int $timestamp = null]: string
Parameters
formatFormat accepted by DateTimeInterface::format[].
timestamp The optional timestamp parameter is an int Unix timestamp that defaults to the current local time if timestamp is omitted or null. In other words, it defaults to the value of
time[].
Return Values
Returns a formatted date string. If a non-numeric value is used for timestamp, false is returned and an E_WARNING level error is emitted.
Errors/Exceptions
Every call to a date/time function will generate a
E_WARNING if the time zone is not valid. See also date_default_timezone_set[]
Changelog
| 8.0.0 | timestamp is nullable now.
|
Examples
Example #1 date[] examples
You can prevent a recognized character in the format string from being expanded by escaping it with a preceding backslash. If the character with a backslash is already a special sequence, you may need to also escape the backslash.
Example #2 Escaping characters in date[]
It is possible to use date[] and mktime[] together to find dates in the future or the past.
Example #3 date[] and mktime[] example
Note:
This can be more reliable than simply adding or subtracting the number of seconds in a day or month to a timestamp because of daylight saving time.
Some examples of date[] formatting. Note that you should escape any other characters, as any which currently have a special meaning will produce undesirable results, and other characters may be assigned meaning in future PHP versions. When escaping, be sure to use single quotes to prevent characters like \n from becoming newlines.
Example #4 date[] Formatting
To format dates in other languages, IntlDateFormatter::format[] can be used instead of date[].
Notes
Note:
To generate a timestamp from a string representation of the date, you may be able to use strtotime[]. Additionally, some databases have functions to convert their date formats into timestamps [such as MySQL's » UNIX_TIMESTAMP function].
See Also
- DateTimeImmutable::__construct[] - Returns new DateTimeImmutable object
- DateTimeInterface::format[] - Returns date formatted according to given format
- gmdate[] - Format a GMT/UTC date/time
- idate[] - Format a local time/date part as integer
- getdate[] - Get date/time information
- getlastmod[] - Gets time of last page modification
- mktime[] - Get Unix timestamp for a date
- IntlDateFormatter::format[] - Format the date/time value as a string
- time[] - Return current Unix timestamp
- Predefined DateTime Constants
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