1.import datetime
常用方法：
ttimedelta() 括号里默认为days，进行别的单位运算可以加上如hours = 1这样。除了进行减法运算，还可以进行加法运算。
>>> a = datetime.datetime.now() - datetime.timedelta(3) >>> a datetime.datetime(2018, 4, 8, 18, 11, 17, 128037) >>> a = datetime.datetime.now() - datetime.timedelta(days = 5) >>> a datetime.datetime(2018, 4, 6, 18, 11, 37, 759721) >>> a = datetime.datetime.now() - datetime.timedelta(hours = 3) >>> a datetime.datetime(2018, 4, 11, 15, 11, 51, 8094)
2.replace（）
在括号里写入需要替换的年月日，即可替换。
>>> import datetime >>> a = datetime.datetime.now() >>> a datetime.datetime(2018, 4, 11, 18, 23, 19, 153333) >>> a.replace(year = 2016) datetime.datetime(2016, 4, 11, 18, 23, 19, 153333) >>> a.replace(month = 9) datetime.datetime(2018, 9, 11, 18, 23, 19, 153333)
原文：https://www.cnblogs.com/Roc-Atlantis/p/8797531.html