Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression

/
/
gxis

Test String

Code Generator

Generated Code

// include the latest version of the regex crate in your Cargo.toml extern crate regex; use regex::Regex; fn main() { let regex = Regex::new(r#"(?xis)(?(DEFINE) (?<XHTML> (?&comment)*\s* (?&DOCTYPE) (?&comment)*\s* (?&HTML) (?&comment)*\s* ) # HTML element (?<HTML> <html(?&attrs)?>(?&content)<\/html> ) # Match content (?<content> \s* (?: ((?&tag) | [^<>]+)\s* )* ) # General tag (?<tag> <((?&tagname))(?&attrs)?\s*(?: \/>| >\s*(?&content)\s* <\/\g'-1'> )|(?&comment) ) # Attributes (?<attrs>\s+ # The name (?&keyword) ( \s*=\s* (?: (?&keyword)|(?&string) ) )? (?&attrs)? ) (?<string> "(?:\\.|.)+?"| '(?:\\.|.)+?' ) (?<comment> \s*<!--(.+?)-->\s* ) # Match keyword (?<keyword>[^\s\/>"'=]+) # Match tag name (?<tagname>(?!xml)[A-Za-z_][A-Za-z\d_.-]*) # DOCTYPE expression (?<DOCTYPE> <!doctype\s+x?html\s*(public\s*(?&string))?(\s+(?&string))*> ) ) ^\s*(?&XHTML)\s*$"#).unwrap(); let string = "<!-- test --> <!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.0 Frameset//EN\" \"http://www.w3.org/TR/xhtml1/DTD/xhtml1-frameset.dtd\"> <html goat:style=\"''inva'lid css I know\">textttt<head></head><body><div class=\"onfoodstamps\"><div class=\"upper\">foo<p>ayyy</p>bar</div>baz</div><br/></head></html>"; // result will be an iterator over tuples containing the start and end indices for each match in the string let result = regex.captures_iter(string); for mat in result { println!("{:?}", mat); } }

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Rust, please visit: https://docs.rs/regex/latest/regex/