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"
"
g

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"to=<(?P<email>\S+)>,\srelay=(?!10\.10\.10\.).+dsn=(?P<dsn>\d+\.\d+\.\d+),\sstatus=(?!sent)").unwrap(); let string = "2016-10-17T00:00:00.028777+03:00 postfix/smtp[6628]: 878A13DCA5: to=<govorok@gmail.com>, relay=gmail-smtp-in.l.google.com[173.194.220.27]:25, delay=0.47, delays=0.01/0/0.12/0.35, dsn=2.0.0, status=sent (250 2.0.0 OK 1476651600 79si16679285lja.36 - gsmtp) 2016-10-17T00:00:00.029273+03:00 postfix/qmgr[4674]: 878A13DCA5: removed 2016-10-17T00:00:00.037122+03:00 postfix/smtpd[6697]: 0906DA5: client=unknown[192.168.2.74] 2016-10-17T00:00:00.039621+03:00 postfix/cleanup[6713]: 0906DA5: message-id=<20161016210000.0906DA5@mrelay-h3.hh.ru> 2016-10-17T00:00:00.040403+03:00 postfix/smtp[6690]: C5670B9: to=<daler_rajabov@inbox.ru>, relay=mxs.mail.ru[217.69.139.150]:25, delay=0.23, delays=0.01/0/0.02/0.2, dsn=2.0.0, status=1s3ent (250 OK id=1bvsXH-0003Cb-Rp)"; // 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/