Python中datetime和string转换和日期比较

1、str类型转成datetime

>>> import time
>>> import datetime
>>> date_str = '2017-06-07'
>>> date_time = datetime.datetime.strptime(date_str, "%Y-%m-%d")
>>> date_time
datetime.datetime(2017, 6, 7, 0, 0)
>>>

2、datetime转str

>>> date_time.strftime("%Y-%m-%d")
'2017-06-07'
>>>

3、日期比较(< > =)

>>> date1 = "2017-06-07"
>>> date2 = "2017-06-09"
# 注意在转换过程中date1和date2必须是str类型！！
>>> date1 = datetime.datetime.strptime(date1,'%Y-%m-%d').date()
>>> date2 = datetime.datetime.strptime(date2,'%Y-%m-%d').date()
>>> print date1, date2
2017-06-07 2017-06-09
>>> print date1 > date2
False
>>> print date1 < date2
True
>>>