[Python]datetime常用的几个操作

#coding: utf-8

''' 日期相关的操作 '''

from datetime import datetime
from datetime import timedelta

DATE_FMT = '%Y-%m-%d'
DATETIME_FMT = '%Y-%m-%d %H:%M:%S'
DATE_US_FMT = '%d/%m/%Y'

'''
格式化常用的几个参数
Y ： 1999
y ：99
m : mouth 02 12 
M : minute 00-59
S : second
d : day
H : hour
'''

def dateToStr(date):
    '''把datetime类型的时间格式化自己想要的格式'''
    return datetime.strftime(date, DATETIME_FMT)

def strToDate(strdate):
    '''把str变成日期用来做一些操作'''
    return datetime.strptime(strdate, DATETIME_FMT) 

def timeElement():
    '''获取一个时间对象的各个元素'''
    now = datetime.today()
    print 'year: %s  month: %s  day: %s' %(now.year, now.month, now.day)
    print 'hour: %s  minute: %s  second: %s' %(now.hour, now.minute, now.second)
    print 'weekday: %s ' %(now.weekday()+1)  #一周是从0开始的

def timeAdd():
    '''
    时间的加减，前一天后一天等操作 
    datetime.timedelta([days[, seconds[, microseconds[, milliseconds[, minutes[, hours[, weeks]]]]]]]) 
    参数可以是正数也可以是负数 
    得到的对象可以加也可以减 乘以数字和求绝对值
    '''
    atime = timedelta(days=-1)
    now = datetime.strptime('2001-01-30 11:01:02', DATETIME_FMT)
    print now + atime
    print now - abs(atime)
    print now - abs(atime)*31

import calendar
def lastFirday():
     today = datetime.today()
     targetDay = calendar.FRIDAY
     thisDay = today.weekday()
     de = (thisDay - targetDay) % 7
     res = today - timedelta(days=de)
     print res 
     
def test():
    #print dateToStr(datetime.today())
    #print strToDate('2013-01-31 12:00:01')
    #timeElement()
    #timeAdd()
    #lastFirday()


if __name__=='__main__':
    test()