[英]Why \g<0> behaves differently than \0 in re.sub?
I'm using Python 3.3 我正在使用Python 3.3
re.sub("(.)(.)",r"\2\1\g<0>","ab") returns baab
BUT 但
re.sub("(.)(.)",r"\2\1\0","ab") returns ba
Is this a bug in the sub method or does the sub method not recognize \\0 on purpose for some reason? 这是sub方法中的错误还是由于某种原因sub方法无法识别\\ 0?
As written on this page , the \\0
is interpreted as the null character ( \\x00
) and group number start at 1 in Python (according to the re
module documentation): 如本页所示 ,
\\0
被解释为空字符( \\x00
),组编号从Python开始为1(根据re
模块文档):
\\number
\\数
Matches the contents of the group of the same number.
匹配相同编号的组的内容。 Groups are numbered starting from 1 .
组从1开始编号 。 For example,
(.+) \\1
matches 'the the' or '55 55', but not 'thethe' (note the space after the group).例如,
(.+) \\1
匹配'the'或'55 55',但不匹配'thethe'(注意组后面的空格)。 This special sequence can only be used to match one of the first 99 groups.此特殊序列只能用于匹配前99个组中的一个。 If the first digit of number is 0 , or number is 3 octal digits long, it will not be interpreted as a group match , but as the character with octal value number.
如果数字的第一个数字是0 ,或者数字是3个八进制数字长, 则不会将其解释为组匹配 ,而是解释为具有八进制数值的字符。 Inside the '[' and ']' of a character class, all numeric escapes are treated as characters.
在字符类的'['和']'内,所有数字转义都被视为字符。
Also, according to the page previously linked, it's not a bug but a desired behaviour (this is obvious, since it's documented). 此外,根据之前链接的页面,它不是一个bug而是一个期望的行为(这很明显,因为它已被记录)。
\\0
is interpreted as an escape for null \\x00
, and re
does not recognize it as a capture group. \\0
被解释为null \\x00
的转义\\x00
,并且re
不会将其识别为捕获组。
Reference: 参考:
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