This is documentation for Mathematica 6, which was
based on an earlier version of the Wolfram Language.

# RegularExpression

 RegularExpression["regex"]represents the generalized regular expression specified by the string "regex".
• 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 ci 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, ... 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 nonwhitespace 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 upper and lower case 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 x:expr can be set up in regular expression strings using (regex).
• Within a regular expression string, \\n represents the substring matched by the n parenthesized regular expression object (regex).
• 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 parenthesized regular expression object in regex. \$0 represents the whole matched string.
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]=
 Scope   (21)
New in 5.1