Descriptionstring strftime ( string format [, int timestamp])
Returns a string formatted according to the given format string using the given timestamp or the current local time if no timestamp is given. Month and weekday names and other language dependent strings respect the current locale set with setlocale().
The following conversion specifiers are recognized in the format string:
%a - abbreviated weekday name according to the current locale
%A - full weekday name according to the current locale
%b - abbreviated month name according to the current locale
%B - full month name according to the current locale
%c - preferred date and time representation for the current locale
%C - century number (the year divided by 100 and truncated to an integer, range 00 to 99)
%d - day of the month as a decimal number (range 01 to 31)
%D - same as %m/%d/%y
%e - day of the month as a decimal number, a single digit is preceded by a space (range ' 1' to '31')
%g - like %G, but without the century.
%G - The 4-digit year corresponding to the ISO week number (see %V). This has the same format and value as %Y, except that if the ISO week number belongs to the previous or next year, that year is used instead.
%h - same as %b
%H - hour as a decimal number using a 24-hour clock (range 00 to 23)
%I - hour as a decimal number using a 12-hour clock (range 01 to 12)
%j - day of the year as a decimal number (range 001 to 366)
%m - month as a decimal number (range 01 to 12)
%M - minute as a decimal number
%n - newline character
%p - either `am' or `pm' according to the given time value, or the corresponding strings for the current locale
%r - time in a.m. and p.m. notation
%R - time in 24 hour notation
%S - second as a decimal number
%t - tab character
%T - current time, equal to %H:%M:%S
%u - weekday as a decimal number [1,7], with 1 representing Monday
Sun Solaris seems to start with Sunday as 1 although ISO 9889:1999 (the current C standard) clearly specifies that it should be Monday.
%U - week number of the current year as a decimal number, starting with the first Sunday as the first day of the first week
%V - The ISO 8601:1988 week number of the current year as a decimal number, range 01 to 53, where week 1 is the first week that has at least 4 days in the current year, and with Monday as the first day of the week. (Use %G or %g for the year component that corresponds to the week number for the specified timestamp.)
%W - week number of the current year as a decimal number, starting with the first Monday as the first day of the first week
%w - day of the week as a decimal, Sunday being 0
%x - preferred date representation for the current locale without the time
%X - preferred time representation for the current locale without the date
%y - year as a decimal number without a century (range 00 to 99)
%Y - year as a decimal number including the century
%Z - time zone or name or abbreviation
%% - a literal `%' character
Note: Not all conversion specifiers may be supported by your C library, in which case they will not be supported by PHP's strftime(). Additionally, not all platforms support negative timestamps, therefore your date range may be limited to no earlier than the unix epoch. This means that e.g. %e, %T, %R and %D (there might be more) and dates prior to Jan 1, 1970 will not work on Windows, some Linux distributions, and a few other operating systems. For Windows systems a complete overview of supported conversion specifiers can be found at this MSDN website.
Note: %G and %V, which are based on ISO 8601:1988 week numbers can give unexpected (albiet correct) results if the numbering system is not thoroughly understood. See %V above and example below.
Example 2. ISO 8601:1988 week number example