Predefined Constants

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# Predefined Constants

The `DATE_*` constants are defined and offer standard date representations, which can be used along with the date format functions (like date()).

Available `returnFormat` for date_sunrise() and date_sunset()
Warning

These constants are deprecated as of PHP 8.4.0. The corresponding date_sunrise() and date_sunset() functions are deprecated as of PHP 8.1.0.

`SUNFUNCS_RET_TIMESTAMP` (int)
  Timestamp
`SUNFUNCS_RET_STRING` (int)
  Hours:minutes (example: `08:02`)
`SUNFUNCS_RET_DOUBLE` (int)
  Hours as floating point number (example `8.75`)

`DATE_*` constants
`DATE_ATOM` (string)
  Atom (example: `2005-08-15T15:52:01+00:00`)
`DATE_COOKIE` (string)
  HTTP Cookies (example: `Monday, 15-Aug-2005 15:52:01 UTC`)
`DATE_ISO8601` (string)
  ISO-8601 (example: `2005-08-15T15:52:01+0000`)

  > Note: This format is not compatible with ISO-8601, but is left this way for backward compatibility reasons. Use `DATE_ISO8601_EXPANDED`, `DATE_ATOM` for compatibility with ISO-8601 instead (ref ISO8601:2004 section 4.3.3 clause d).

`DATE_ISO8601_EXPANDED` (string)
  ISO-8601 Expanded (example: `+10191-07-26T08:59:52+01:00`)

  > Note: This format allows for year ranges outside of ISO-8601's normal range of `0000`-`9999` by always including a sign character. It also ensures that the timezone part (`+01:00`) is compatible with ISO-8601.

`DATE_RFC822` (string)
  RFC 822 (example: `Mon, 15 Aug 05 15:52:01 +0000`)
`DATE_RFC850` (string)
  RFC 850 (example: `Monday, 15-Aug-05 15:52:01 UTC`)
`DATE_RFC1036` (string)
  RFC 1036 (example: `Mon, 15 Aug 05 15:52:01 +0000`)
`DATE_RFC1123` (string)
  RFC 1123 (example: `Mon, 15 Aug 2005 15:52:01 +0000`)
`DATE_RFC7231` (string)
  RFC 7231 (as of PHP 7.0.19 and 7.1.5) (example: `Sat, 30 Apr 2016 17:52:13 GMT`)
`DATE_RFC2822` (string)
  RFC 2822 (example: `Mon, 15 Aug 2005 15:52:01 +0000`)
`DATE_RFC3339` (string)
  Same as `DATE_ATOM`.
`DATE_RFC3339_EXTENDED` (string)
  RFC 3339 EXTENDED format (example: `2005-08-15T15:52:01.000+00:00`)
`DATE_RSS` (string)
  RSS (example: `Mon, 15 Aug 2005 15:52:01 +0000`). Alias of `DATE_RFC1123`.
`DATE_W3C` (string)
  World Wide Web Consortium (example: `2005-08-15T15:52:01+00:00`). Alias of `DATE_RFC3339`.