Python简单日期算术
示例
日期不是孤立存在的。通常，您需要查找日期之间的时间量或确定明天是几号。这可以使用timedelta对象来完成
import datetime
today = datetime.date.today()
print('Today:', today)
yesterday = today - datetime.timedelta(days=1)
print('Yesterday:', yesterday)
tomorrow = today + datetime.timedelta(days=1)
print('Tomorrow:', tomorrow)
print('Time between tomorrow and yesterday:', tomorrow - yesterday)这将产生类似于以下结果：
Today: 2016-04-15 Yesterday: 2016-04-14 Tomorrow: 2016-04-16 Difference between tomorrow and yesterday: 2 days, 0:00:00