BUILT-IN MATHEMATICA SYMBOL

# RegularExpression

RegularExpression["regex"]
represents the generalized regular expression specified by the string .

## DetailsDetails

• 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 [c1-c2] any character in the range - [^c1c2...] any character except the p* p repeated zero or more times p+ p repeated one or more times p? zero or one occurrence of p p{m,n} p repeated between m and n times p*?,p+?,p?? the shortest consistent strings that match (p1p2...) strings matching the sequence , , ... p1|p2 strings matching or
• 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: , , , , , , , , , , , , , .
• 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 Mathematica patterns such as can be set up in regular expression strings using (regex).
• Within a regular expression string, \\n represents the substring matched by the parenthesized regular expression object (regex).
• For the purpose of functions such as StringReplace and StringCases, any appearing in the right-hand side of a rule RegularExpression["regex"]->rhs is taken to correspond to the substring matched by the parenthesized regular expression object in regex. represents the whole matched string.

## ExamplesExamplesopen allclose all

### Basic Examples (2)Basic Examples (2)

Find words involving the characters a, b, c, d, e:

 Out[1]=

Equivalent form using string patterns:

 Out[2]=

Decide whether the string consists of words and whitespace:

 Out[1]=

Equivalent form using string patterns:

 Out[2]=