C # Regular Expression basics

C # Regular Expression basics

Metacharacters

Character	Description
^	Match the start position of the line
$	Match the end position of the line
B	Match the start or end of a word
.	Matches any character other than a newline symbol
W	Match word characters (including letters, numbers, underscores, and Chinese characters)
W	Match any non-word characters (including letters, numbers, underscores, and Chinese characters)
S	Match any white space characters, such as spaces, tabs, line breaks, and so on
S	Matching Non-white-space characters
D	Match an arbitrary number
D	Match a number that is not arbitrary

Common Character Set:

Character	Description
.	Matches any character other than a newline symbol
W	Match word characters (including letters, numbers, underscores, and Chinese characters)
W	Match any non-word characters (including letters, numbers, underscores, and Chinese characters)
S	Match any white space characters, such as spaces, tabs, line breaks, and so on
S	Matching Non-white-space characters
D	Match an arbitrary number
D	Match a number that is not arbitrary
[ABCD]	Match any character in the character set combination
[^ABCD]	Matches any character other than the character set combination
[0-9a-za-z]	Matches any number, letter (uppercase and lowercase letters) and underscores, equivalent to W
[^0-9a-za-z]	Matches numbers, letters (uppercase and lowercase letters) and underscores, equal to W
P{name}	Matches any of the characters in the named character class specified by the {name}
P{name}	Matches any character outside of the named-named character class specified by {name}

Common escape characters:

Character	Description
A	Bell Alarm u0007
B	In a regular expression, the boundary of a word, or backspace u0008 if it is in a character class.
T	tab u0009
R	return character u000d
V	Vertical tab U000B
F	Change page character u000c
N	Line feed u000a
E	Fallback character u001b
40	Match ASCII characters to 8 binary numbers
X20	Match ASCII characters with hexadecimal representation
Cc	ASCII control characters, such as CTRL + C
u0020	Match Unicode characters with hexadecimal representation

Common Qualifier characters:

Character	Description
N	Repeat n times
{N,}	Repeat at least n times
{N,m}	Repeat at least n times, up to M times
*	Repeat at least 0 times, equal to {0,}
+	Repeat at least 1 times, equal to {1,}
？	Repeat 0 or 1 times, equivalent to {0,1}
*？	Use the duplicate first match as little as possible
+	Use as few repetitions as possible, but use at least once
？？	Use 0 repetitions or one repetition
{n}?	Equal to {n}
{N,}?	Use duplicates as much as possible but use at least n times
{n,m}?	Between n times and M times, using as few repetitions as possible

Replace character : |

Example: Three fixed telephone numbers in some parts of China

0D{2}-D{8}|0D{3}-D{7}|0D{3}-D{8}

Grouping characters : ()

Example: Match a simple IP address

(d{1,3}.) {3}d{1,3}