Python对时间的转换

1.将字符串的时间转换为时间戳
方法:
a = "2013-10-10 23:40:00"
将其转换为时间数组
import time
timeArray = time.strptime(a, "%Y-%m-%d %H:%M:%S")
转换为时间戳:
timeStamp = int(time.mktime(timeArray))
timeStamp == 1381419600

2.字符串格式更改
如a = "2013-10-10 23:40:00",想改为 a = "2013/10/10 23:40:00"
方法:先转换为时间数组,然后转换为其他格式
timeArray = time.strptime(a, "%Y-%m-%d %H:%M:%S")
otherStyleTime = time.strftime("%Y/%m/%d %H:%M:%S", timeArray)

3.时间戳转换为指定格式日期:
方法一:
利用localtime()转换为时间数组,然后格式化为需要的格式,如
timeStamp = 1381419600
timeArray = time.localtime(timeStamp)
otherStyleTime = time.strftime("%Y-%m-%d %H:%M:%S", timeArray)
otherStyletime == "2013-10-10 23:40:00"

方法二:
import datetime
timeStamp = 1381419600
dateArray = datetime.datetime.utcfromtimestamp(timeStamp)
otherStyleTime = dateArray.strftime("%Y-%m-%d %H:%M:%S")
otherStyletime == "2013-10-10 23:40:00"

4.获取当前时间并转换为指定日期格式
方法一:
import time
获得当前时间时间戳
now = int(time.time()) ->这是时间戳
转换为其他日期格式,如:"%Y-%m-%d %H:%M:%S"
timeArray = time.localtime(timeStamp)
otherStyleTime = time.strftime("%Y-%m-%d %H:%M:%S", timeArray)

方法二:
import datetime
获得当前时间
now = datetime.datetime.now() ->这是时间数组格式
转换为指定的格式:
otherStyleTime = now.strftime("%Y-%m-%d %H:%M:%S")

5.获得三天前的时间
方法:
import time
import datetime
先获得时间数组格式的日期
threeDayAgo = (datetime.datetime.now() - datetime.timedelta(days = 3))
转换为时间戳:
timeStamp = int(time.mktime(threeDayAgo.timetuple()))
转换为其他字符串格式:
otherStyleTime = threeDayAgo.strftime("%Y-%m-%d %H:%M:%S")
注:timedelta()的参数有:days,hours,seconds,microseconds

6.给定时间戳,计算该时间的几天前时间:
timeStamp = 1381419600
先转换为datetime
import datetime
import time
dateArray = datetime.datetime.utcfromtimestamp(timeStamp)
threeDayAgo = dateArray - datetime.timedelta(days = 3)
参考5,可以转换为其他的任意格式了

import datetime

def days(str1,str2):
    date1=datetime.datetime.strptime(str1[0:10],"%Y-%m-%d")
    date2=datetime.datetime.strptime(str2[0:10],"%Y-%m-%d")
    num=(date1-date2).days
    return num

def months(str1,str2):
    year1=datetime.datetime.strptime(str1[0:10],"%Y-%m-%d").year
    year2=datetime.datetime.strptime(str2[0:10],"%Y-%m-%d").year
    month1=datetime.datetime.strptime(str1[0:10],"%Y-%m-%d").month
    month2=datetime.datetime.strptime(str2[0:10],"%Y-%m-%d").month
    num=(year1-year2)*12+(month1-month2)
    return num
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一下方法已经在python3.4之后就过时了。

>>> import datetime

>>> (datetime.datetime(2010,03,01) - datetime.datetime(2010,02,01)).days

# 当天所在当月的几号

datetime.datetime.now().day

# 当前月份

datetime.datetime.now().mouth

# 当前年份

datetime.datetime.now().year

print ((datetime.datetime.now()-datetime.timedelta(days=1)).strftime("%Y-%m-%d %H:%M"))

print ((datetime.datetime.now()-datetime.timedelta(minutes=1)).strftime("%Y-%m-%d %H:%M"))

print ((datetime.datetime.now()-datetime.timedelta(seconds=1)).strftime("%Y-%m-%d %H:%M"))

now = datetime.datetime.now()

# 3天前

three_days_ago = now + datetime.timedelta(-3)

# 3天前的前12分钟0秒

three_days_ago = now + datetime.timedelta(-3,-12,0)

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