Regular Expressions and C#, .NET

.

Matches any single character. An example of this is the regular expression s.t would match the strings sat, sit, but not sight.

$

Matches the end of a line. For instance, the regular expression reason$ would match the end of the string "He has a reason" but not the string "He has his reasons"

^

Matches the beginning of a line. For instance, the regular expression ^Where would match the beginning of the string "Where is my cap" but would not match "Do you know Where it is " .

*

Matches zero or more occurrences of the character immediately preceding. For example, the regular expression .* means match any number of any characters.

This is a escape or quoting character. The character after this is treated as an ordinary character. For example, ^ is used to match the caret sign character (^) rather than the beginning of a line. Similarly, the expression . is used to match the “.” character .

[ ]


[c1-c2]


[^c1-c2]
 

Matches any one of the characters between the brackets.
For example, the regular expression s[ia]t matches sat, sit, but not set.

Ranges of characters can specified by using a hyphen.
For example, the regular expression [0-9] means match any digit. Multiple ranges can be specified as well. The regular expression [A-Za-z] means match any upper or lower case letter.

To match any character except those in the range, the complement range, use the caret as the first character after the opening bracket.
For example, the expression [^123a-z] will match any characters except 1,2, 3, and lower case letters.

< >

Matches the beginning ( < ) or end ( >) or a word. For example, < THE< _fckxhtmljob="2" span > matches on "the" in the string "for the older" but does not match "the" in "rather"

( )

Treat the expression between ( and ) as a group. Also, saves the characters matched by the expression into temporary holding areas. Up to nine pattern matches can be saved in a single regular expression. They can be referenced as 1 through 9.

|

Or two conditions together. For example (him|her) matches the line "it belongs to him" and matches the line "it belongs to her" but does not match the line "it belongs to them."

+

Matches one or more occurrences of the character or regular expression immediately preceding. For example, the regular expression 9+ matches 9, 99, 999.

?

Matches 0 or 1 occurrence of the character or regular expression immediately preceding.

{i}

{i,j}

Match a specific number of instances or instances within a range of the preceding character.
For example, the expression A[0-9]{3} will match "A" followed by exactly 3 digits. That is, it will match A123 but not A1234.

The expression [0-9]{4,6} any sequence of 4, 5, or 6 digits

b

Matches a backspace

t

Matches a tab

r

Matches a carriage return

v

Matches a vertical tab

f

Matches a form feed

n

Matches a new line

e

Matches an escape

40

Matches an ASCII character as octal (up to three digits);

x20

Matches an ASCII character using hexadecimal representation (exactly two digits).

cC

Matches an ASCII control character; for example, cC is control-C.

u0020

Matches a Unicode character using hexadecimal representation (exactly four digits).

Character

Description

$number

Substitutes the last substring matched by group number number (decimal).

${name}

Substitutes the last substring matched by a (? ) group.

$$

Substitutes a single "$" literal.

$&

Substitutes a copy of the entire match itself.

$`

Substitutes all the text of the input string before the match.

$'

Substitutes all the text of the input string after the match.

$+

Substitutes the last group captured.

$_

Substitutes the entire input string.

Character class

Description

.

Matches any character except n. If modified by the Singleline option, a period character matches any character.

[aeiou]

Matches any single character included in the specified set of characters.

[^aeiou]

Matches any single character not in the specified set of characters.

[0-9a-fA-F]

Use of a hyphen (–) allows specification of contiguous character ranges.

p{name}

Matches any character in the named character class specified by {name}.

P{name}

Matches text not included in groups and block ranges specified in {name}.

w

Matches any word character.

W

Matches any non-word character.