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.NET and C#  Regular Expression

Microsoft's .NET framework provides a consistent and powerful set of regular expression classes for all .NET implementations. The following sections list the .NET regular expression syntax, the core .NET classes.Microsoft's .NET uses a Traditional NFA match engine. For an explanation of the rules behind a Traditional NFA engine.

.NET defines its regular expression support in the System.Text.RegularExpressions module. The RegExp( ) constructor handles regular expression creation, and the rest of the RegExp methods handle pattern matching. The Groups and Match classes contain information about each match. C#'s raw string syntax, @"", allows you to define regular expression patterns without having to escape embedded backslashes.

Match

Properties

public bool Success

Indicates whether the match was successful.

public string Value

Text of the match.

public int Length

Number of characters in the matched text.

public int Index

Zero-based character index of the start of the match.

public GroupCollection Groups

A GroupCollection object where Groups[0].value contains the text of the entire match, and each additional Groups element contains the text matched by a capture group.

Methods

public Match NextMatch( )

Return a Match object for the next match of the regex in the input string.

public virtual string Result(string result)

Return result with special replacement sequences replaced by values from the previous match.

public static Match Synchronized(Match inner)

Return a Match object identical to inner, except also safe for multithreaded use.

Properties

public bool Success

True if the group participated in the match.

public string Value

Text captured by this group.

public int Length

Number of characters captured by this group.

public int Index

Zero-based character index of the start of the text captured by this group.

Metacharacters representations

Sequence	Meaning
\a	Alert (bell), x07.
\b	Backspace, x08, supported only in character class.
\e	ESC character, x1B.
\n	Newline, x0A.
\r	Carriage return, x0D.
\f	Form feed, x0C.
\t	Horizontal tab, x09.
\v	Vertical tab, x0B.
\0octal	Character specified by a two-digit octal code.
\xhex	Character specified by a two-digit hexadecimal code.
\uhex	Character specified by a four-digit hexadecimal code.
\cchar	Named control character.

Character classes

Class	Meaning
[...]	A single character listed or contained within a listed range.
[^...]	A single character not listed and not contained within a listed range.
.	Any character, except a line terminator (unless single-line mode, s).
\w	Word character,or [a-zA-Z_0-9] in ECMAScript mode.
\W	Non-word character,or [^a-zA-Z_0-9] in ECMAScript mode.
\d	Digit,or [0-9] in ECMAScript mode.
\D	Non-digit,or [^0-9] in ECMAScript mode.
\s	Whitespace character,or [ \f\n\r\t\v] in ECMAScript mode.
\S	Non-whitespace character,or [^ \f\n\r\t\v] in ECMAScript mode.
\p{prop}	Character contained by given Unicode block or property.
\P{prop}	Character not contained by given Unicode block or property.

Comments and mode modifiers

Modifier/sequence	Mode character	Meaning
Singleline	s	Dot (.) matches any character, including a line terminator.
Multiline	m	^ and $ match next to embedded line terminators.
IgnorePatternWhitespace	x	Ignore whitespace and allow embedded comments starting with #.
IgnoreCase	i	Case-insensitive match based on characters in the current culture.
CultureInvariant	i	Culture-insensitive match.
ExplicitCapture	n	Allow named capture groups, but treat parentheses as non-capturing groups.
Compiled		Compile regular expression.
RightToLeft		Search from right to left, starting to the left of the start position.
ECMAScript		Enables ECMAScript compliance when used with IgnoreCase or Multiline.
(?imnsx-imnsx)		Turn match flags on or off for rest of pattern.
(?imnsx-imnsx:...)		Turn match flags on or off for the rest of the subexpression.
(?#...)		Treat substring as a comment.
#...		Treat rest of line as a comment in /x mode.

Grouping, capturing, conditional, and control

Sequence	Meaning
(...)	Grouping. Submatches fill \1,\2,... and $1, $2,....
\n	In a regular expression, match what was matched by the nth earlier submatch.
$n	In a replacement string, contains the nth earlier submatch.
(?<name>...)	Captures matched substring into group, name.
(?:...)	Grouping-only parentheses, no capturing.
(?>...)	Disallow backtracking for subpattern.
...|...	Alternation; match one or the other.
*	Match 0 or more times.
+	Match 1 or more times.
?	Match 1 or 0 times.
{n}	Match exactly n times.
{n,}	Match at least n times.
{x,y}	Match at least x times, but no more than y times.
*?	Match 0 or more times, but as few times as possible.
+?	Match 1 or more times, but as few times as possible.
??	Match 0 or 1 times, but as few times as possible.
{n,}?	Match at least n times, but as few times as possible.
{x,y}?	Match at least x times, no more than y times, but as few times as possible.

Example

//Match super-Man, Superman, SUPER-MAN, etc.
namespace Regex_PocketRef
{
  using System.Text.RegularExpressions;

  class SimpleMatchTest
  {
    static void Main(  )
    {
      string dailybugle = "Super-Man Menaces City!";

      string regex = "super[- ]?man";
  
    if (Regex.IsMatch(dailybugle, regex, RegexOptions.IgnoreCase)) {
      //do something
    }  
  }
}

Ajax

Regular Expression