Python正则表达式匹配日期 [英] Python regex to match dates

问题描述

我在Python中使用什么正则表达式来匹配这样的日期： 11/12/98？

What regular expression in Python do I use to match dates like this: "11/12/98"?

推荐答案

代替使用正则表达式，通常最好将字符串解析为 datetime.datetime 对象：

Instead of using regex, it is generally better to parse the string as a datetime.datetime object:

In [140]: datetime.datetime.strptime("11/12/98","%m/%d/%y")
Out[140]: datetime.datetime(1998, 11, 12, 0, 0)

In [141]: datetime.datetime.strptime("11/12/98","%d/%m/%y")
Out[141]: datetime.datetime(1998, 12, 11, 0, 0)

然后，您可以将日期，月份和年份（以及小时，分钟和秒）作为 datetime.datetime 对象的属性来访问：

You could then access the day, month, and year (and hour, minutes, and seconds) as attributes of the datetime.datetime object:

In [143]: date.year
Out[143]: 1998

In [144]: date.month
Out[144]: 11

In [145]: date.day
Out[145]: 12

要测试以斜杠分隔的数字序列是否表示有效日期，可以使用 try..except 块。无效的日期将引发 ValueError ：

To test if a sequence of digits separated by forward-slashes represents a valid date, you could use a try..except block. Invalid dates will raise a ValueError:

In [159]: try:
   .....:     datetime.datetime.strptime("99/99/99","%m/%d/%y")
   .....: except ValueError as err:
   .....:     print(err)
   .....:     
   .....:     
time data '99/99/99' does not match format '%m/%d/%y'

---

如果您需要搜索更长的字符串以获取日期，则可以使用
使用正则表达式来搜索以正斜杠分隔的数字：

---

If you need to search a longer string for a date, you could use regex to search for digits separated by forward-slashes:

In [146]: import re
In [152]: match = re.search(r'(\d+/\d+/\d+)','The date is 11/12/98')

In [153]: match.group(1)
Out[153]: '11/12/98'

当然，无效日期也将匹配：

Of course, invalid dates will also match:

In [154]: match = re.search(r'(\d+/\d+/\d+)','The date is 99/99/99')

In [155]: match.group(1)
Out[155]: '99/99/99'

要检查 match.group（1 ）返回有效的日期字符串，然后可以使用 datetime.datetime.strptime 进行解析，如上所示。

To check that match.group(1) returns a valid date string, you could then parsing it using datetime.datetime.strptime as shown above.

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