Python正则表达式,匹配字符串的绝对开头,之前没有别的

编辑:

您可以使用非分隔的捕获组和re.match(它锚定到字符串的开头):

>>> from re import match
>>> strs = ["CON.txt", "LPT1.png", "COM1.html", "CON.jpg"]
>>> # This can be customized to what you want
>>> # Right now, it is matching .jpg and .png files with the proper beginning
>>> [x for x in strs if match("(?:CON|COM1|LPT1)\.(?:jpg|png)$", x)]
['LPT1.png', 'CON.jpg']
>>>

以下是正则表达式的细分:

(?:CON|COM1|LPT1)  # CON, COM1, or LPT1
\.                 # A period
(?:jpg|png)        # jpg or png
$                  # The end of the string

您可能还希望添加(?i)到模式的开头,以便进行不区分大小写的匹配.