日期和字符串转换

from datetime import datetime

# 当前时间
now =  datetime.now()

# 格式化输出日期
now.strftime('%Y-%m-%d %H:%M:%S')

# 字符串转datetime
s = '2020-12-25 16:26:23'
dt= datetime.strptime(s, '%Y-%m-%d %H:%M:%S')

日期运算

from datetime import timedelta

# timedelta 构造方法 timedelta(days=0, seconds=0, microseconds=0, milliseconds=0, minutes=0, hours=0, weeks=0)

delta = timedelta(days=1)

# timedelta 支持和数字做乘除运算，但不能做加减运算
# x = delta -1 非法，TypeError: unsupported operand type(s) for -: 'datetime.timedelta' and 'int'

delta = delta * 1 # 合法

# datetime、time 类型支持和 timedelta 之间做加减运算
tomorrow = now + delta
yesterday = now - delta
print(tomorrow.strftime('%Y-%m-%d'))
print(yesterday.strftime('%Y-%m-%d'))