$smarty = new Smarty;
$smarty->assign('yesterday', strtotime('-1 day'));
$smarty->display('index.tpl');
index.tpl:
{$smarty.now|date_format}
{$smarty.now|date_format:"%A, %B %e, %Y"}
{$smarty.now|date_format:"%H:%M:%S"}
{$yesterday|date_format}
{$yesterday|date_format:"%A, %B %e, %Y"}
{$yesterday|date_format:"%H:%M:%S"}

Feb 6, 2001
Tuesday, February 6, 2001
:33:00
Feb 5, 2001
Monday, February 5, 2001
:33:00

%a - abbreviated weekday name according to the current locale
（根据当地格式输出“星期”缩写格式）
%A - full weekday name according to the current locale
（根据当地格式输出“星期”全称格式）
%b - abbreviated month name according to the current locale
（根据当地格式输出“月”缩写格式）
%B - full month name according to the current locale
（根据当地格式输出“月”全称格式）
%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 00 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 - Week-based year within century [00,99]
%G - Week-based year, including the century [0000,9999]
%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)
%k - Hour (24-hour clock) single digits are preceded by a blank. (range 0 to 23)
%l - hour as a decimal number using a 12-hour clock, single digits preceeded by
a space (range 1 to 12)
%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
%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.
%w - day of the week as a decimal, Sunday being 0
%W - week number of the current year as a decimal number, starting with the first Monday as the first day of the first week
%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