python之模块datetime 常见操作

# -*- coding: utf-8 -*-
#python 27
#xiaodeng
#python之模块datetime
#http://blog.sina.com.cn/s/blog_6c3748830100ypt9.html
#http://blog.sina.com.cn/s/blog_dd49240d0102w0y6.html


import datetime
'''
NAME:
datetime - Fast implementation of the datetime type.
'''
#help(datetime),datetime模块下的几个类：
'''
datetime.date
    .today()
datetime.time
datetime.datetime
    .now()
    .timedelta(days=1)
datetime.timedelta
datetime.tzinfo
'''


import datetime
import time


#今天日期
today=datetime.date.today()
print today#2015-09-05


#日期对象;date(year, month, day) --> date object
s=datetime.date(2015,9,1)
print s,type(s)#2015-09-01


#获取当前系统时间
date=datetime.datetime.now()
print date#2015-09-05 16:34:41.460000


#返回昨天的日期
def getYesterday():
    today=datetime.date.today()
    oneday=datetime.timedelta(days=1)
    yesterday=today-oneday
    return yesterday


#获取当前年份，月份等，是一个字符串
def getYear():
    year=str(datetime.date.today())[0:4]
    month=str(datetime.date.today())[5:7]
    return year,month

print 'getYear:',getYear()


#返回当前时间的时间戳
s=time.time()
print s


#计算2个日期的天数差
import datetime
d1=datetime.datetime(2015,9,1)
d2=datetime.datetime(2015,9,5)
print d2-d1#4 days, 0:00:00
s=(d2-d1).days
print s#4天


#计算当前时间向后10小时的时间
import datetime
d1=datetime.datetime.now()
d2=d1+datetime.timedelta(hours=10)#注意hours，是有s的
print d2.ctime()#Sun Sep  6 02:53:21 2015


#计算上个月的月份
import time
last_month = time.localtime()[1]-1 or 12
print last_month