如何使用 strptime 解析 str(my_datetime)?
问题描述
这是 默认字符串表示日期时间:
>>> from datetime import datetime, timezone
>>> dt = datetime(2017, 1, 1, tzinfo=timezone.utc)
>>> print(dt)
2017-01-01 00:00:00+00:00
用 datetime.strptime
解析的正确格式字符串是什么?也就是说,用什么格式代替???"?始终具有以下不变量:
What is the correct format string to parse that with datetime.strptime
? That is, what format goes in place of the "???" to consistently have the following invariant:
>>> dt == datetime.strptime(str(dt), "???")
True
解决方案
注意 str(d)
被记录为等同于 d.isoformat(' ')
.这以 %Y-%m-%d %H:%M:%S
(2017-01-01 00:00:00
) 开头,然后:
Note that str(d)
is documented as being equivalent to d.isoformat(' ')
. This starts with %Y-%m-%d %H:%M:%S
(2017-01-01 00:00:00
), but then:
- 要么没有,要么没有
.%f
,这取决于微秒部分是否为非零. - 根据实例是否支持时区,要么没有任何内容,要么没有类似
+HH:MM
的偏移量.
- Either has nothing or
.%f
, depending whether the microseconds part is nonzero. - Either has nothing or an offset like
+HH:MM
, depending whether the instance is timezone-aware.
datetime.strptime
不支持可选部分,因此没有一个 format
参数可以匹配所有可能的输出.
datetime.strptime
doesn't have support for optional parts, therefore there isn't a single format
parameter that can match all of the possible outputs.
在 Python 3.7+ 中,您可以使用 datetime.fromisoformat
解析 datetime.isoformat
输出.由 Paul Ganssle 在 issue15873 中贡献.
In Python 3.7+, you can use datetime.fromisoformat
to parse datetime.isoformat
output. Contributed by Paul Ganssle in issue15873.
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