RegularExpression ["regex"]
represents the generalized regular expression specified by the string "regex".
RegularExpression
RegularExpression ["regex"]
represents the generalized regular expression specified by the string "regex".
Details
- RegularExpression can be used to represent classes of strings in functions like StringMatchQ , StringReplace , StringCases , and StringSplit .
- RegularExpression supports standard regular expression syntax of the kind used in typical string manipulation languages.
- The following basic elements can be used in regular expression strings:
-
c the literal character c. any character except newline[c1c2…] any of the characters ci[c1-c2] any character in the range c1–c2[^c1c2…] any character except the cip* p repeated zero or more timesp+ p repeated one or more timesp? zero or one occurrence of pp{m,n} p repeated between m and n timesp*?,p+?,p?? the shortest consistent strings that match(p1p2…) strings matching the sequence p1, p2, …p1|p2 strings matching p1 or p2
- The following represent classes of characters:
-
\\d digit 0–9\\D nondigit\\s space, newline, tab, or other whitespace character\\S non-whitespace character\\w word character (letter, digit, or _)\\W nonword character[[:class:]] characters in a named class[^[:class:]] characters not in a named class
- The following named classes can be used: alnum, alpha, ascii, blank, cntrl, digit, graph, lower, print, punct, space, upper, word, xdigit.
- The following represent positions in strings:
-
^ the beginning of the string (or line)$ the end of the string (or line)\\b word boundary\\B anywhere except a word boundary
- The following set options for all regular expression elements that follow them:
-
(?i) treat uppercase and lowercase as equivalent (ignore case)(?m) make ^ and $ match start and end of lines (multiline mode)(?s) allow . to match newline(?-c) unset options
- \\., \\[, etc. represent literal characters ., [, etc.
- Analogs of named Wolfram Language patterns such as x:expr can be set up in regular expression strings using (regex).
- Within a regular expression string, \\gn represents the substring matched by the n^(th) parenthesized regular expression object (regex). The shorter \\n is often equivalent to \\gn.
- For the purpose of functions such as StringReplace and StringCases , any $n appearing in the right‐hand side of a rule RegularExpression ["regex"]->rhs is taken to correspond to the substring matched by the n^(th) parenthesized regular expression object in regex. 0ドル represents the whole matched string.
Examples
open all close allBasic Examples (2)
Find words involving the characters a, b, c, d, e:
Equivalent form using string patterns:
Decide whether the string consists of words and whitespace:
Equivalent form using string patterns:
Scope (22)
Basic Constructs (17)
Extract any character except newline:
Either of the characters "a" and "b":
Any character between "a" and "e", including "a" and "e":
Any character except "a" and "1":
Any digit repeated one or more times:
The character "a" repeated 2 or 3 times:
Any digit:
Nondigit characters:
Space, newline, tab, or other whitespace character:
Non-whitespace characters:
Word characters:
Nonword characters:
Find all uppercase letters:
Split a string at the beginning of a new line:
Split a string at the end of a new line:
Insert a character at the boundary of each word:
Split a string at every character except at the boundary of a word:
Compound Constructs (5)
StringExpression can contain RegularExpression objects:
Conditional patterns:
Use alternatives to match one or more line breaks:
Non-greedy matches are done by appending a question mark "?" to the quantifiers:
The 1ドル refers to the letter matched by (.):
Numbered subpatterns:
Properties & Relations (3)
Use StringMatchQ to determine string pattern matches:
Use StringCases to find matching substrings:
Use StringSplit to split a string into substrings using a delimiter pattern:
See Also
StringExpression StringCases StringReplace SearchQueryString
Function Repository: ToRegularExpression BioSequenceToRegularExpression
Tech Notes
History
Introduced in 2004 (5.1)
Text
Wolfram Research (2004), RegularExpression, Wolfram Language function, https://reference.wolfram.com/language/ref/RegularExpression.html.
CMS
Wolfram Language. 2004. "RegularExpression." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/RegularExpression.html.
APA
Wolfram Language. (2004). RegularExpression. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/RegularExpression.html
BibTeX
@misc{reference.wolfram_2025_regularexpression, author="Wolfram Research", title="{RegularExpression}", year="2004", howpublished="\url{https://reference.wolfram.com/language/ref/RegularExpression.html}", note=[Accessed: 05-December-2025]}
BibLaTeX
@online{reference.wolfram_2025_regularexpression, organization={Wolfram Research}, title={RegularExpression}, year={2004}, url={https://reference.wolfram.com/language/ref/RegularExpression.html}, note=[Accessed: 05-December-2025]}