datetime模块

1. timedelta方法的使用 ```python from datetime import datetime, timedelta now = datetime.now() #显示系统时间戳 print(now) old1 = now - timedelta(hours = 1) #计算间隔1h的方式 print(old1) old2 = now - timedelta(minutes = 60) #计算间隔1h使用分钟方式 print(old2) old3 = now - timedelta(seconds = 3600) #计算间隔1h 使用秒方式 print(old3)

2020-05-03 15:28:48.947680 2020-05-03 14:28:48.947680 2020-05-03 14:28:48.947680 2020-05-03 14:28:48.947680

2. strftime方法的使用-日期格式格式化操作。
```python
from datetime import datetime, timedelta
now = datetime.now()
print(now)
print(now.strftime('%Y%m%d %H:%M:%S'))
----------------------------
2020-05-03 15:36:03.480008
20200503 15:36:03

1. 日期增减标准化输出 ```python from datetime import datetime, timedelta now = datetime.now() print(now) print(now.strftime(‘%Y%m%d %H:%M:%S’)) old1 = now - timedelta(minutes = 30) print(old1.strftime(‘%Y%m%d %H:%M:%S’)) now2 = datetime.now().date() # 计算天数 old2 = now2- timedelta(days = 1) print(now2) print(old2)

2020-05-03 15:48:12.737297 20200503 15:48:12 20200503 15:18:12 2020-05-03 2020-05-02

4. 元组与日期格式的转换
```python
from datetime import datetime
time_tuple = (2020, 12, 29, 12, 30, 20)
time = datetime(*time_tuple[0:6]).strftime('%Y%m%d %H:%M:%S')
print(time)
---------------------------
20201229 12:30:20