%a Weekday as Sun, Mon
%A Weekday as full name as Sunday, Monday
%w Weekday as decimal no as 0,1,2...
%d Day of month as 01,02
%b Months as Jan, Feb
%B Months as January, February
%m Months as 01,02
%y Year without century as 11,12,13
%Y Year with century 2011,2012
%H 24 Hours clock from 00 to 23
%I 12 Hours clock from 01 to 12
%p AM, PM
%M Minutes from 00 to 59
%S Seconds from 00 to 59
%f Microseconds 6 decimal numbers
import datetime
d =datetime.datetime.strptime("01/27/2012","%m/%d/%Y").strftime('%m/%d/%Y')
print d
01/27/2012