PHP : Dates and Times - [3.5] Printing a Date or Time in a Specified Format

3.5.1 Problem

You need to print out a date or time formatted in a particular way.

3.5.2 Solution

Use date( ) or strftime( ):

print strftime('%c');
print date('m/d/Y');
Tue Jul 30 11:31:08 2002
07/30/2002

3.5.3 Discussion

Both date( ) and strftime( ) are flexible functions that can produce a formatted time string with a variety of components. The formatting characters for these functions are listed in Table 3-3. The Windows column indicates whether the formatting character is supported by strftime( ) on Windows systems.

Table 3-3. strftime( ) and date( ) format characters

Type	strftime( )	date( )	Description	Range	Windows
Hour	%H	H	Hour, numeric, 24-hour clock	00-23	Yes
Hour	%I	h	Hour, numeric, 12-hour clock	01-12	Yes
Hour	%k		Hour, numeric, 24-hour clock, leading zero as space	0-23	No
Hour	%l		Hour, numeric, 12-hour clock, leading zero as space	1-12	No
Hour	%p	A	AM or PM designation for current locale		Yes
Hour	%P	a	am/pm designation for current locale		No
Hour		G	Hour, numeric, 24-hour clock, leading zero trimmed	0-23	No
Hour		g	Hour, numeric, 12-hour clock, leading zero trimmed	0-1	No
Minute	%M	I	Minute, numeric	00-59	Yes
Second	%S	s	Second, numeric	00-61[1]	Yes
Day	%d	d	Day of the month, numeric	01-31	Yes
Day	%e		Day of the month, numeric, leading zero as space	1-31	No
Day	%j	z	Day of the year, numeric	001-366 for strftime( ); 0-365 for date( )	Yes
Day	%u		Day of the week, numeric (Monday is 1)	1-7	No
Day	%w	w	Day of the week, numeric (Sunday is 0)	0-6	Yes
Day		j	Day of the month, numeric, leading zero trimmed	1-31	No
Day		S	English ordinal suffix for day of the month, textual	"st," "th," "nd," "rd"	No
Week	%a	D	Abbreviated weekday name, text for current locale		Yes
Week	%A	l	Full weekday name, text for current locale		Yes
Week	%U		Week number in the year; numeric; first Sunday is the first day of the first week	00-53	Yes
Week	%V	W	ISO 8601:1988 week number in the year; numeric; week 1 is the first week that has at least 4 days in the current year; Monday is the first day of the week	01-53	No
Week	%W		Week number in the year; numeric; first Monday is the first day of the first week	00-53	Yes
Month	%B	F	Full month name, text for current locale		Yes
Month	%b	M	Abbreviated month name, text for current locale		Yes
Month	%h		Same as %b		No
Month	%m	m	Month, numeric	01-12	Yes
Month		n	Month, numeric, leading zero trimmed	1-12	No
Month		t	Month length in days, numeric	28, 29, 30, 31	No
Year	%C		Century, numeric	00-99	No
Year	%g		Like %G, but without the century	00-99	No
Year	%G		ISO 8601 year with century; numeric; the four-digit year corresponding to the ISO week number; same as %y except if the ISO week number belongs to the previous or next year, that year is used instead		No
Year	%y	y	Year without century, numeric	00-99	Yes
Year	%Y	Y	Year, numeric, including century		Yes
Year		L	Leap year flag (yes is 1)	0, 1	No
Timezone	%z	O	Hour offset from GMT, +/-HHMM (e.g., -0400, +0230)	-1200-+1200	Yes, but acts like %Z
Timezone	%Z	T	Time zone, name, or abbreviation; textual		Yes
Timezone		I	Daylight saving time flag (yes is 1)	0, 1	No
Timezone		Z	Seconds offset from GMT; west of GMT is negative, east of GMT is positive	-43200-43200	No
Compound	%c		Standard date and time format for current locale		Yes
Compound	%D		Same as %m/%d/%y		No
Compound	%F		Same as %Y-%m-%d		No
Compound	%r		Time in AM or PM notation for current locale		No
Compound	%R		Time in 24-hour notation for current locale		No
Compound	%T		Time in 24-hour notation (same as %H:%M:%S)		No
Compound	%x		Standard date format for current locale(without time)		Yes
Compound	%X		Standard time format for current locale(without date)		Yes
Compound		r	RFC 822 formatted date (e.g., "Thu, 22 Aug 2002 16:01:07 +0200")		No
Other	%s	U	Seconds since the epoch		No
Other		B	Swatch Internet time		No
Formatting	%%		Literal % character		Yes
Formatting	%n		Newline character		No
Formatting	%t		Tab character		No

^[1] The range for seconds extends to 61 to account for leap seconds.

The first argument to each function is a format string, and the second argument is an epoch timestamp. If you leave out the second argument, both functions default to the current date and time. While date( ) and strftime( ) operate over local time, they each have UTC-centric counterparts (gmdate( ) and gmstrftime( )).

The formatting characters for date( ) are PHP-specific, but strftime( ) uses the C-library strftime( ) function. This may make strftime( ) more understandable to someone coming to PHP from another language, but it also makes its behavior slightly different on various platforms. Windows doesn't support as many strftime( ) formatting commands as most Unix-based systems. Also, strftime( ) expects its formatting characters to each be preceded by a % (think printf( )), so it's easier to produce strings with lots of interpolated time and date values in them.

For example, at 12:49 P.M. on July 15, 2002, the code to print out:

It's after 12 pm on July 15, 2002

with strftime( ) looks like:

print strftime("It's after %I %P on %B %d, %Y");

With date( ) it looks like:

print "It's after ".date('h a').' on '.date('F d, Y');

Non-date-related characters in a format string are fine for strftime( ), because it looks for the % character to decide where to interpolate the appropriate time information. However, date( ) doesn't have such a delimiter, so about the only extras you can tuck into the formatting string are spaces and punctuation. If you pass strftime( )'s formatting string to date( ):

print date("It's after %I %P on %B%d, %Y");

you'd almost certainly not want what you'd get:

131'44 pmf31eMon, 15 Jul 2002 12:49:44 -0400 %1 %P o7 %742%15, %2002

To generate time parts with date( ) that are easy to interpolate, group all time and date parts from date( ) into one string, separating the different components with a delimiter that date( ) won't translate into anything and that isn't itself part of one of your substrings. Then, using explode( ) with that delimiter character, put each piece of the return value from date( ) in an array, which is easily interpolated in your output string:

$ar = explode(':',date("h a:F d, Y"));
print "It's after $ar[0] on $ar[1]";