Syntax

	This section is under construction.

Metacharacters Defined || Metacharacter Examples MChar || Definition || Pattern || Sample Matches ^ Start of a string. || ^abc || abc, abcdefg, abc123, ... $ End of a string. || abc$ || abc, endsinabc, 123abc, ... . Any character (except \n newline) || a.c || abc, aac, acc, adc, aec, ... | Alternation. {...} Explicit quantifier notation. [...] Explicit set of characters to match. (...) Logical grouping of part of an expression.

0 or more of previous expression.

+ 1 or more of previous expression. ? 0 or 1 of previous expression; also forces minimal matching when an expression might match several strings within a search string. \ Preceding one of the above, it makes it a literal instead of a special character. Preceding a special matching character, see below.

bill|ted ted, bill ab{2}c abbc a[bB]c abc, aBc (abc){2} abcabc ab*c ac, abc, abbc, abbbc, ... ab+c abc, abbc, abbbc, ... ab?c ac, abc a\sc a c

Character Escapes Escaped Char Description ordinary characters Characters other than . $ ^ { [ ( | ) ] } * + ? \ match themselves. \a Matches a bell (alarm) \u0007. \b Matches a backspace \u0008 if in a []; otherwise matches a word boundary (between \w and \W characters). \t Matches a tab \u0009. \r Matches a carriage return \u000D. \v Matches a vertical tab \u000B. \f Matches a form feed \u000C. \n Matches a new line \u000A. \e Matches an escape \u001B. \040 Matches an ASCII character as octal (up to three digits); numbers with no leading zero are backreferences if they have only one digit or if they correspond to a capturing group number. (For more information, see Backreferences.) For example, the character \040 represents a space. \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 a hexadecimal representation (exactly four digits). \* When followed by a character that is not recognized as an escaped character, matches that character. For example, \* is the same as \x2A.

Character Classes Char Class Description . Matches any character except \n. If modified by the Singleline option, a period character matches any character. For more information, see Regular Expression Options. [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}. Supported names are Unicode groups and block ranges. For example, Ll, Nd, Z, IsGreek, IsBoxDrawing. \P{name} Matches text not included in groups and block ranges specified in {name}. \w Matches any word character. Equivalent to the Unicode character categories [\p{Ll}\p{Lu}\p{Lt}\p{Lo}\p{Nd}\p{Pc}]. If ECMAScript-compliant behavior is specified with the ECMAScript option, \w is equivalent to [a-zA-Z_0-9]. \W Matches any nonword character. Equivalent to the Unicode categories [^\p{Ll}\p{Lu}\p{Lt}\p{Lo}\p{Nd}\p{Pc}]. If ECMAScript-compliant behavior is specified with the ECMAScript option, \W is equivalent to [^a-zA-Z_0-9]. \s Matches any white-space character. Equivalent to the Unicode character categories [\f\n\r\t\v\x85\p{Z}]. If ECMAScript-compliant behavior is specified with the ECMAScript option, \s is equivalent to [ \f\n\r\t\v]. \S Matches any non-white-space character. Equivalent to the Unicode character categories [^\f\n\r\t\v\x85\p{Z}]. If ECMAScript-compliant behavior is specified with the ECMAScript option, \S is equivalent to [^ \f\n\r\t\v]. \d Matches any decimal digit. Equivalent to \p{Nd} for Unicode and [0-9] for non-Unicode, ECMAScript behavior. \D Matches any nondigit. Equivalent to \P{Nd} for Unicode and [^0-9] for non-Unicode, ECMAScript behavior.

Symbol	Function
[\^$.\|?*+()	Special characters any other will match themselves
\	Escapes special characters and treat as literal
*	Repeat the previous item zero or more times
.	Single character except line break characters
.*	Match zero or more characters
^	Match at the start of a line/string
$	Match at the end of a line/string
.$	Match a single character at the end of line/string
^ $	Match line with a single space
[^A-Z]	Match any line beginning with any char from A to Z

Examples

For IP Addresses:

1. To Match upto 999.999.999.999:

\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b

OR shortened with a quantifier to:

\b(?:\d{1,3}\.){3}\d{1,3}\b

2. To match exactly upto 255.255.255.255:

 
\b(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b

OR shortened with a quantifier to:

\b(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b

For Credit Card numbers:

1. Visa card numbers start with a 4. New cards have 16 digits. Old cards have 13:

^4[0-9]{12}(?:[0-9]{3})?$

2. MasterCard numbers start with the numbers 51 through 55. All have 16 digits:

^5[1-5][0-9]{14}$

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