python datetime格式化參數

坑爹啊，記憶力不行，老是記不住，都用了這麼久了，記在這裡以後來翻。

Directive	Meaning	Notes
%a	Locale’s abbreviated weekdayname.
%A	Locale’s full weekday name.
%b	Locale’s abbreviated monthname.
%B	Locale’s full month name.
%c	Locale’s appropriate date andtime representation.
%d	Day of the month as a decimalnumber [01,31].
%f	Microsecond as a decimalnumber [0,999999], zero-paddedon the left	(1)
%H	Hour (24-hour clock) as adecimal number [00,23].
%I	Hour (12-hour clock) as adecimal number [01,12].
%j	Day of the year as a decimalnumber [001,366].
%m	Month as a decimal number[01,12].
%M	Minute as a decimal number[00,59].
%p	Locale’s equivalent of eitherAM or PM.	(2)
%S	Second as a decimal number[00,61].	(3)
%U	Week number of the year(Sunday as the first day ofthe week) as a decimal number[00,53]. All days in a newyear preceding the firstSunday are considered to be inweek 0.	(4)
%w	Weekday as a decimal number[0(Sunday),6].
%W	Week number of the year(Monday as the first day ofthe week) as a decimal number[00,53]. All days in a newyear preceding the firstMonday are considered to be inweek 0.	(4)
%x	Locale’s appropriate daterepresentation.
%X	Locale’s appropriate timerepresentation.
%y	Year without century as adecimal number [00,99].
%Y	Year with century as a decimalnumber.
%z	UTC offset in the form +HHMMor -HHMM (empty string if thethe object is naive).	(5)
%Z	Time zone name (empty stringif the object is naive).
%%	A literal '%' character.

http://docs.python.org/library/datetime.html#strftime-strptime-behavior