python 正则表达式语法进修条记

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正则表达式是一个非凡的字符序列，它能辅佐你利便的搜查一个字符串是否与某种模式匹配。这篇文章首要先容了python 正则表达式语法记录,必要的伴侣可以参考下

正则表达式(regular expression)描写了一种字符串匹配的模式（pattern），可以用来搜查一个串是否含有某种子串、将匹配的子串替代可能从某个串中取出切合某个前提的子串等。

Python 自1.5版本起增进了re 模块，它提供 Perl 气魄威风凛凛的正则表达式模式。

re 模块使 Python 说话拥有所有的正则表达式成果。

compile 函数按照一个模式字符串和可选的符号参数天生一个正则表达式工具。该工具拥有一系列要领用于正则表达式匹配和替代。

本文重点给各人先容python 正则表达式语法。

The special characters are:

"." Matches any character except a newline.

"^" Matches the start of the string.

"$" Matches the end of the string or just before the newline at

the end of the string.

"*" Matches 0 or more (greedy) repetitions of the preceding RE.

Greedy means that it will match as many repetitions as possible.

"+" Matches 1 or more (greedy) repetitions of the preceding RE.

"?" Matches 0 or 1 (greedy) of the preceding RE.

*?,+?,?? Non-greedy versions of the previous three special characters.

{m,n} Matches from m to n repetitions of the preceding RE.

{m,n}? Non-greedy version of the above.

"" Either escapes special characters or signals a special sequence.

[] Indicates a set of characters.

A "^" as the first character indicates a complementing set.

"|" A|B, creates an RE that will match either A or B.

(...) Matches the RE inside the parentheses.

The contents can be retrieved or matched later in the string.

(?aiLmsux) Set the A, I, L, M, S, U, or X flag for the RE (see below).

(?:...) Non-grouping version of regular parentheses.

(?P...) The substring matched by the group is accessible by name.

(?P=name) Matches the text matched earlier by the group named name.

(?#...) A comment; ignored.

(?=...) Matches if ... matches next, but doesn't consume the string.

(?!...) Matches if ... doesn't match next.

(?<=...) Matches if preceded by ... (must be fixed length).

(?

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