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

/
/

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"\s+Content-[Tt]ype:\s*\S+").unwrap(); let string = "Accept-Ranges: bytes Cache-Control: max-age=604800 Content-Type: text/html Date: Fri, 14 Aug 2015 17:45:05 GMT Etag: \"359670651\" Expires: Fri, 21 Aug 2015 17:45:05 GMT Last-Modified: Fri, 09 Aug 2013 23:54:35 GMT Server: ECS (fty/2FA4) X-Cache: HIT x-ec-custom-error: 1 Content-Length: 1270 - 0%[ ] 0 --.-KB/s <!doctype html> <html> <head> <title>Example Domain</title> <meta charset=\"utf-8\" /> <meta http-equiv=\"Content-type\" content=\"text/html; charset=utf-8\" /> <meta name=\"viewport\" content=\"width=device-width, initial-scale=1\" /> <style type=\"text/css\"> body { background-color: #f0f0f2; margin: 0; padding: 0; font-family: \"Open Sans\", \"Helvetica Neue\", Helvetica, Arial, sans-serif; } div { width: 600px; margin: 5em auto; padding: 50px; background-color: #fff; border-radius: 1em; } a:link, a:visited { color: #38488f; text-decoration: none; } @media (max-width: 700px) { body { background-color: #fff; } div { width: auto; margin: 0 auto; border-radius: 0; padding: 1em; } } </style> </head> <body> <div> <h1>Example Domain</h1> <p>This domain is established to be used for illustrative examples in documents. You may use this domain in examples without prior coordination or asking for permission.</p> <p><a href=\"http://www.iana.org/domains/example\">More information...</a></p> </div> </body> </html>"; // result will be a tuple containing the start and end indices for the first match in the string let result = regex.captures(string); let (start, end) = match result { Some((s, e)) => (s, e), None => { // ... } }; println!("{}", &string[start, end]); }

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/