Date and Time in PHP
May 28, 2002
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PHP's date functions are powerful,
flexible, and surprisingly easy to use. This article guides you through
the functions, explaining the concept of a Unix timestamp, which is at the
heart of most of the functions, and shows you how easy it is to master
these often-misused functions.
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Displaying the current date and time with the date() function
The most used function is one that returns the current date and time, and
allows you to format as you wish - the date function. And using it is very
simple: date("formatting_option").
There are a whole range of possible formatting options. You can add your own
characters inside the format string too. Here's a list of all the formatting
characters.
| a |
"am" or "pm" |
| A |
"AM" or "PM" |
| B |
Swatch Internet time |
| d |
day of the month, 2 digits with leading zeros; i.e. "01" to "31" |
| D |
day of the week, textual, 3 letters; i.e. "Fri" |
| F |
month, textual, long; i.e. "January" |
| g |
hour, 12-hour format without leading zeros; i.e. "1" to "12" |
| G |
hour, 24-hour format without leading zeros; i.e. "0" to "23" |
| h |
hour, 12-hour format; i.e. "01" to "12" |
| H |
hour, 24-hour format; i.e. "00" to "23" |
| i |
minutes; i.e. "00" to "59" |
| I (capital i) |
"1" if Daylight Savings Time, "0" otherwise. |
| j |
day of the month without leading zeros; i.e. "1" to "31" |
| l (lowercase 'L') |
day of the week, textual, long; i.e. "Friday" |
| L |
boolean for whether it is a leap year; i.e. "0" or "1" |
| m |
month; i.e. "01" to "12" |
| M |
month, textual, 3 letters; i.e. "Jan" |
| n |
month without leading zeros; i.e. "1" to "12" |
| r |
RFC 822 formatted date; i.e. "Thu, 21 Dec 2000 16:01:07 +0200" (added
in PHP 4.0.4) |
| s |
seconds; i.e. "00" to "59" |
| S |
English ordinal suffix, textual, 2 characters; i.e. "th", "nd" |
| t |
number of days in the given month; i.e. "28" to "31" |
| T |
Timezone setting of this machine; i.e. "MDT" |
| U |
seconds since the epoch |
| w |
day of the week, numeric, i.e. "0" (Sunday) to "6" (Saturday) |
| Y |
year, 4 digits; i.e. "1999" |
| y |
year, 2 digits; i.e. "99" |
| z |
day of the year; i.e. "0" to "365" |
| Z |
timezone offset in seconds (i.e. "-43200" to "43200"). The offset for
timezones west of UTC is always negative, and for those east of UTC is
always positive. |
Some examples:
//returns the day (0-31), month (3 letters) and year(4 digits)
print date("d-M-Y");
displays:
09-May-2002
The '-' characters are my formatting strings. I could have used anything else
too:
print date("d^^^M^^^Y");
displays:
09^^^May^^^2002
print date("D dS M,Y h:i a");
displays:
Thu 09th May,2002 06:13 pm
Read through the list above - you'll find most possibilities have been
thought of, and if all you're trying to do is format the date and/or time,
you'll have no problems.
The date function is not only tied to displaying the local datetime on the
server. You can also pass it a timestamp (often called a Unix timestamp, since
it developed on Unix machines), which is the number of seconds since January 1,
1970 (starting with 1 second after midnight). By default the date function takes
the current timestamp, but you can pass any timestamp you want, for example:
print date("l M dS, Y, H:i:s",5678)
displays:
Thursday Jan 01st, 1970, 03:34:38
Be careful though with trying to use one of the reserved format strings as
your own format string. If you tried to do something like:
print date("The time is: H.i");
you'd get something like the unexpected result of:
SAST11e 314605e 4638: 23.46
Of the first word, 'The', the 'T' returns the time zone setting of the
machine running PHP (SAST in my case), 'h' returns the hour, while at least the
'e' comes though correctly. But from there it's all downhill. In order to get
the correct display, you'll need to escape the characters with a backslash, as
follows:
print date("\T\he \\t\i\m\e \i\s: H.i");
which displays what we'd originally hoped for:
The time is: 23.54
Just for good measure we had to escape the 't' twice, since '\t' is the
special character for a tab. Not the easiest to read at all! Later in this
article, we look at the strftime() function, which makes formatting complex
strings easier, and also helps with other languages.
There is also a related gmdate() function, which is the same as date(0 except
that it returns the Greenwich Mean Time.
Date and Time in PHP
Returning the current timestamp with the time() function
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