用python实现的时间函数

lomg

#-*-coding:utf-8-*-
import datetime, calendar
def getYesterday():
today=datetime.date.today()
oneday=datetime.timedelta(days=1)
yesterday=today-oneday
return yesterday
def getToday():
return datetime.date.today()  
#获取给定参数的前几天的日期，返回一个list
def getDaysByNum(num):
today=datetime.date.today()
oneday=datetime.timedelta(days=1)   
li=[]     
for i in range(0,num):
#今天减一天，一天一天减
today=today-oneday
#把日期转换成字符串
#result=datetostr(today)
li.append(datetostr(today))
return li
#将字符串转换成datetime类型
def strtodatetime(datestr,format):   
return datetime.datetime.strptime(datestr,format)
#时间转换成字符串,格式为2008-08-02
def datetostr(date):  
return   str(date)[0:10]
#两个日期相隔多少天，例：2008-10-03和2008-10-01是相隔两天
def datediff(beginDate,endDate):
format="%Y-%m-%d";
bd=strtodatetime(beginDate,format)
ed=strtodatetime(endDate,format)   
oneday=datetime.timedelta(days=1)
count=0
while bd!=ed:
ed=ed-oneday
count+=1
return count
#获取两个时间段的所有时间,返回list
def getDays(beginDate,endDate):
format="%Y-%m-%d";
bd=strtodatetime(beginDate,format)
ed=strtodatetime(endDate,format)
oneday=datetime.timedelta(days=1)
num=datediff(beginDate,endDate)+1
li=[]
for i in range(0,num):
li.append(datetostr(ed))
ed=ed-oneday
return li
#获取当前年份 是一个字符串
def getYear():
return str(datetime.date.today())[0:4]
#获取当前月份 是一个字符串
def getMonth():
return str(datetime.date.today())[5:7]
#获取当前天 是一个字符串
def getDay():
return str(datetime.date.today())[8:10]   
def getNow():
return datetime.datetime.now()

print getToday()
print getYesterday()
print getDaysByNum(3)
print getDays('2008-10-01','2008-10-05')
print '2008-10-04 00:00:00'[0:10]
print str(getYear())+getMonth()+getDay()
print getNow()