C# Regex Pattern in .Net
C# Regular Expressions
A regular expression is an object that describes a pattern of characters or it's called a rational expression. In this blog post I have listed down c# regex pattern with a sequence of symbols, metacharacters, operators and quantifiers. Please find the below c# regular expression with c# regex example:
regex reference 
Character

Description

\

Marks the next
character as either a special character or escapes a literal. For example,
"n" matches the character "n". "\n" matches a
newline character. The sequence "\\" matches "\" and
"\(" matches "(".
Note: double quotes
may be escaped by doubling them: "<a href=""...>"

^

Depending on whether
the MultiLine option is set, matches the position before the first character
in a line, or the first character in the string.

$

Depending on whether
the MultiLine option is set, matches the position after the last character in
a line, or the last character in the string.

*

Matches the
preceding character zero or more times. For example, "zo*" matches
either "z" or "zoo".

+

Matches the
preceding character one or more times. For example, "zo+" matches
"zoo" but not "z".

?

Matches the
preceding character zero or one time. For example, "a?ve?" matches
the "ve" in "never".

.

Matches any single
character except a newline character.

(pattern)

Matches pattern and remembers the match. The matched
substring can be retrieved from the resulting Matches collection, using Item [0]...[n]. To match parentheses characters ( ), use
"\(" or "\)".

(?<name>pattern)

Matches pattern and gives the match a name.

(?:pattern)

A noncapturing
group

(?=...)

A positive lookahead

(?!...)

A negative lookahead

(?<=...)

A positive
lookbehind .

(?<!...)

A negative
lookbehind .

xy

Matches either x or y. For example, "zwood" matches "z" or
"wood". "(zw)oo" matches "zoo" or
"wood".

{n}

n is a nonnegative
integer. Matches exactly n times. For example, "o{2}" does not match the
"o" in "Bob," but matches the first two o's in
"foooood".

{n,}

n is a nonnegative
integer. Matches at least n times. For example, "o{2,}" does not match the
"o" in "Bob" and matches all the o's in
"foooood." "o{1,}" is equivalent to "o+".
"o{0,}" is equivalent to "o*".

{n,m}

m and n are nonnegative integers. Matches at least n and at most m times. For example, "o{1,3}"
matches the first three o's in "fooooood." "o{0,1}" is
equivalent to "o?".

[xyz]

A character set.
Matches any one of the enclosed characters. For example, "[abc]"
matches the "a" in "plain".

[^xyz]

A negative character
set. Matches any character not enclosed. For example, "[^abc]"
matches the "p" in "plain".

[az]

A range of
characters. Matches any character in the specified range. For example,
"[az]" matches any lowercase alphabetic character in the range
"a" through "z".

[^mz]

A negative range
characters. Matches any character not in the specified range. For example,
"[mz]" matches any character not in the range "m"
through "z".

\b

Matches a word
boundary, that is, the position between a word and a space. For example,
"er\b" matches the "er" in "never" but not the
"er" in "verb".

\B

Matches a nonword
boundary. "ea*r\B" matches the "ear" in "never
early".

\d

Matches a digit
character. Equivalent to [09].

\D

Matches a nondigit
character. Equivalent to [^09].

\f

Matches a formfeed
character.

\k

A backreference to
a named group.

\n

Matches a newline
character.

\r

Matches a carriage
return character.

\s

Matches any white
space including space, tab, formfeed, etc. Equivalent to
"[ \f\n\r\t\v]".

\S

Matches any nonwhite
space character. Equivalent to "[^ \f\n\r\t\v]".

\t

Matches a tab
character.

\v

Matches a vertical
tab character.

\w

Matches any word
character including underscore. Equivalent to "[AZaz09_]".

\W

Matches any nonword
character. Equivalent to "[^AZaz09_]".

\num

Matches num, where num is a positive integer. A reference back to
remembered matches. For example, "(.)\1" matches two consecutive
identical characters.

\n

Matches n, where n is an octal escape value. Octal escape
values must be 1, 2, or 3 digits long. For example, "\11" and
"\011" both match a tab character. "\0011" is the
equivalent of "\001" & "1". Octal escape values must
not exceed 256. If they do, only the first two digits comprise the
expression. Allows ASCII codes to be used in regular expressions.

\xn

Matches n, where n is a hexadecimal escape value. Hexadecimal
escape values must be exactly two digits long. For example, "\x41"
matches "A". "\x041" is equivalent to "\x04"
& "1". Allows ASCII codes to be used in regular expressions.

\un

Matches a Unicode
character expressed in hexadecimal notation with exactly four numeric digits.
"\u0200" matches a space character.

\A

Matches the position
before the first character in a string. Not affected by the MultiLine setting

\Z

Matches the position
after the last character of a string. Not affected by the MultiLine setting.

\G

Specifies that the
matches must be consecutive, without any intervening nonmatching characters.

C# Regex Example: Find the below email address validation using regular expression :
(([\w]+\.)+[\w]+([azAZ]{1}[\w]{2,}))@
I hope you have enjoyed the c#.net programming tips while using regular expression with regex c# example. I would like to have feedback from my blog readers. Your valuable feedback, question, or comments about this article are always welcome.
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