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
No Match

r"
"

Test String

Code Generator

Language

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"X-Gmail-Labels\s*:\s*(?P<X_Gmail_Labels>[\w]+,[\w]+)[\r|\n|\S|\s]+Delivered-To\s*:\s*(?P<delivered_to>[\S]+)[\r|\n|\S|\s]+Subject\s*:\s*(?P<subject>.+)[\r|\n|\S|\s]+From\s*:\s*(?P<from>[^>]+>)").unwrap(); let string = "From 1488780641874111180@xxx Mon Dec 29 12:11:00 2014 X-GM-THRID: 1488780145305309925 X-Gmail-Labels: Sent,Important MIME-Version: 1.0 Received: by 10.52.29.70 with HTTP; Sun, 28 Dec 2014 16:11:00 -0800 (PST) X-Originating-IP: [82.13.144.221] In-Reply-To: <01ff42fddfded95cfa8b14fa5559b0fb.squirrel@webmail04.register.com> References: <01ff42fddfded95cfa8b14fa5559b0fb.squirrel@webmail04.register.com> Date: Mon, 29 Dec 2014 00:11:00 +0000 Delivered-To: hello@domain.co Message-ID: <CAN8wjQQWm33RS-hDdE1k3c6CMOge9-eq=3GrcNssV8gPYi+osA@mail.gmail.com> Subject: Re: test subject: added - 1 From: DG <hello@domain.co> To: info@otherdomain.us Content-Type: multipart/alternative; boundary=001a11c2183a9b3b4e050b4fb549 --001a11c2183a9b3b4e050b4fb549 Content-Type: text/plain; charset=UTF-8 Hey Chris, Is that price for the pass with tax? Also do you have any recommendations for good rental places in town? Cheers, -dave"; // 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/