The regular expression of Python

I. INTRODUCTION

A regular expression (or RE) is a small, highly specialized programming language (in Python) that is embedded in Python and implemented through the RE module and then compiled into a series of bytecode that is then executed by a matching engine written in C

Two. Common operation

1. Character Matching

• • Metacharacters

.		Substituting any character except a newline character, which can match only one of the characters
^		Match beginning
$		Match end of Line
*		Repeat match 0~ multiple times, greedy match
+		Repeat match 1~ multiple times, at least one match
?		Match 0 or one time, optional, up to only one
{}		Determine the number of matches, or range
[]		Commonly used to develop a character set, such as [AB] matches a or b; other metacharacters do not work in [] except for "-" "^"
|		Or
()		Grouping The first group number is 1
\		Translated

• • Special characters

\d		Match any decimal number; it is equivalent to class [0-9].
\d		Matches any non-numeric character; it is equivalent to a class [^0-9]
\s		Match any whitespace character; it is equivalent to class [\t\n\r\f\v]
\s		Matches any non-whitespace character; it is equivalent to a class [^ \t\n\r\f\v]
\w		Match any alphanumeric character; it is equivalent to a class [a-za-z0-9_]
\w		Matches any non-alphanumeric character; it is equivalent to a class [^a-za-z0-9_]
\b		Match a word boundary, that is, the position between the word and the space

The regular expression of Python