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
%d - day of the month as a decimal number (range 00 to 31)
%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 1 to 12)
%M - minute as a decimal number
%p - either `am' or `pm' according to the given time value, or
the corresponding strings for the current locale
%S - second as a decimal number
%U - week number of the current year as a decimal number,
starting with the first Sunday as the first day of the first
week
%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
This example works if you have the respective locales installed
in your system.