The collation of regular expression knowledge points

Locator characters
\b	Match the beginning or end of a word
\b	Match a position that is not the beginning or end of a word
^	Match the start of a string
$	Match the end of a string
Content Matching
\w	Match letters or numbers or underscores or kanji
\w	Matches characters that are not letters or numbers or underscores or kanji
\d	Match numbers
\d	Match non-numeric
\s	Match any of the whitespace characters
\s	Match any non-whitespace character
.	Match any character other than line break
\f	Match a page break
\ n	Match a line break
\ r	Match a carriage return character
\ t	Match a tab
\v	Match a vertical tab
Quantity Matching
*	Repeat 0 or more times
？	Repeat 0 or one time
+	Repeat one or more times
N	Repeat n times
{N,}	Repeat n times, or more
{N,m}	Repeat N to M times
Selectable Options Match
[ABC]	Match any one of the characters in []
[0-9a-z]	Match any one of the characters in 0-9 or A-Z
[^0-9]	Match any one character beyond 0-9
Branch conditions
|	Branching conditions (or logic)	When using branching conditions, be aware of the order of each condition. logically more rigorous match expressions should be placed in front . When matched, each condition will be tested from left to right, and if a branch is satisfied, it will not be able to control the other conditions .
Group
（）	You can use parentheses to specify sub-expressions (grouping)	For sub-expressions it is possible to set the number of loops uniformly
Backward reference
(exp)	Match exp, and capture text into an automatically named group	Citation: \index Index is the group number assigned from left to right
(? <name>exp)	Match exp, and capture the text to a group named name, or you can write (? ') Name ' exp ')	\k<nmae>
(?: EXP)	Matches exp, does not capture matching text, and does not assign group numbers to this group
0 Wide Assertion
(? =exp)	Matches the position of the exp front [describes the relationship between exp and the previous section]	For example: \b\w+ (? =ing\b) finds the location where the ing\b matches, and then ing\b to the end to determine the content of the \b\w+ match
(? <=exp)	Match the position after exp [describe the relationship between Exp and the back part]	For example: (? <=\bre) \w+\b first find the location of the \bre match, and then \bre to the beginning to determine the content of the \w+\b match
Negative 0 Wide Assertion
(?! Exp	The match is followed by a position that is not exp [describes the relationship between exp and the previous section]	For example: \d{3} (?! \d) First find the string that matches the \d{3}, and then determine that the content behind it does not match \d
(? <!exp)	Match the position of the previous not exp [describe the relationship between Exp and the back part]	For example: (? <![ A-z]) \d{7} First find the string that matches the \d{7} and then determine that the previous content does not match [a-z]
Comments
(? #注释文本)	The content inside the parentheses is a comment
#注释文本	The current line, #之后的内容全部为注释
Greed and laziness
Greedy match: When a regular expression contains a qualifier that can accept duplicates, the usual behavior is to match as many characters as possible (in the premise that the entire expression can be matched).
Lazy match: Just match as few characters as possible. Just add a question mark to the back, and you can convert it.
Match priority: The regular expression has another rule that has a higher priority than the lazy/greedy rule: the first match has the highest priority
*？	Repeat any number of times, but repeat as little as possible
+	Repeat 1 or more times, but repeat as little as possible
？？	Repeat 0 or 1 times, but repeat as little as possible
{n,m}?	Repeat N to M times, but repeat as little as possible
{N,}?	Repeat more than n times, but repeat as little as possible
Processing options (. NET support)
IgnoreCase (ignoring case)	Match is not case-sensitive.
Multiline (multi-line mode)	Change the meaning of ^ and $ so that they match at the beginning and end of each line, and not just at the beginning and ending of the entire string. (In this mode, the exact meaning of $ is: match the position before \ n and the position before the end of the string.)
Singleline (single-line mode)	Change the meaning of the. To make it match every character (including newline characters \ n).
Ignorepatternwhitespace (Ignore whitespace)	Ignores non-escaped whitespace in an expression and enables comments marked by #.
Explicitcapture (Explicit capture)	Only groups that have been explicitly named are captured.
such as: regex regex = new Regex (@ "\ba\w{6}\b", regexoptions.ignorecase);
Note: Multi-line mode and single-line mode can be enabled at the same time, there is no relationship between the two options, except that their names are more similar.

The collation of regular expression knowledge points