python 的time和datetime常用写法

import time
from datetime import datetime
from datetime import timedelta

#打印时间串
print(time.time())#1574387008.6881413

#打印当时时间
print (time.strftime("%Y-%m-%d %H:%M:%S",time.localtime()))#2019-11-22 09:43:28
print (datetime.now().strftime("%Y-%m-%d %H:%M:%S"))#2019-11-22 09:43:28

#时间差的写法
now=datetime.now()
yesterday=now+timedelta(days=-1)
print(now) #2019-11-22 09:43:28.688141
print(yesterday) #2019-11-21 09:43:28.688141
print(yesterday.strftime("%Y-%m-%d %H:%M:%S")) #2019-11-21 09:43:28