python日期、时间、字符串相互转换

在python中，⽇期类型date和⽇期时间类型dateTime是不能⽐较的。

（1）如果要⽐较，可以将dateTime转换为date，date不能直接转换为dateTime

import datetime

dateTime_p = datetime.datetime.now() date_p = dateTime_p.date()

print(dateTime_p) #2019-01-30 15:17:46.573139print(date_p) #2019-01-30

（2）⽇期类型date转换为字符串str

#!/usr/bin/env python3

import datetime

date_p = datetime.datetime.now().date()str_p = str(date_p)

print(date_p,type(date_p)) #2019-01-30 print(str_p,type(str_p)) #2019-01-30

（3）字符串类型str转换为dateTime类型

import datetime

str_p = '2019-01-30 15:29:08'

dateTime_p = datetime.datetime.strptime(str_p,'%Y-%m-%d %H:%M:%S')print(dateTime_p) # 2019-01-30 15:29:08

（4）dateTime类型转为str类型

　　这个地⽅我也不太理解，为什么指定格式⽆效

import datetime

dateTime_p = datetime.datetime.now()

str_p = datetime.datetime.strftime(dateTime_p,'%Y-%m-%d')print(dateTime_p) # 2019-01-30 15:36:19.415157

（5）字符串类型str转换为date类型

#!/usr/bin/env python3import datetimestr_p = '2019-01-30'

date_p = datetime.datetime.strptime(str_p,'%Y-%m-%d').date()print(date_p,type(date_p)) # 2019-01-30

另外dateTime类型和date类型可以直接做加1减1这种操作

#!/usr/bin/env python3import datetime

# today = datetime.datetime.today()

today = datetime.datetime.today().date()

yestoday = today + datetime.timedelta(days=-1)tomorrow = today + datetime.timedelta(days=1)print(today) # 2019-01-30print(yestoday)# 2019-01-29print(tomorrow)# 2019-01-31