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

/
/
gim

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"(?im)^[a-zA-Z0-9_\-\.~]{4,}@[a-zA-Z0-9_\-\.~]{3,6}\.[a-zA-Z]{2,4}$").unwrap(); let string = "info@bvo.global foo..bar+ddddd@baz.com foo@bar.baz.com .foo@bar.baz.com foo.@bar.baz.com foo-bar@baz.com -foo-bar@baz.com foo-bar-@baz.com 客服@买卖.商务 foo@bar.baz foo@.bar.baz foo@bar.baz. foo@bar.baz foo@bar.ba foo@bar.baz.quux foo@bar.b foo@bar.bazquux foo@031.33.7.255 42@255.255.255.255 42@199.1.1.1 42@256.255.255.255 foo@63-character-long-domain-name-which-is-allowed-by-the-standards.com foo@64character-long-domain-name-which-isnt-allowed-by-the-standards.com 255-chàräçter-loñg-emàîl#%address!&with+-some_weird.!?character~combinations'in_it-just-to-fill-üp-the-address-léngth-to-get-to-the-255-character.limit.-This_is_really_starting_to_become_a_quite_long_email_address.-who_would_even_use_something_like_this?@foo.bar short-address-with-illegal-character,in-it@foo.bar 256-character-long.-email#%address!&with+-some_weird.!?character~combinations'in_it-just-to-fill-up-the-address-length-to-get-to-the-255-character.limit.-This_is_really_starting_to_become_a_quite_long_email_address.-who_would_even_use_something_like_this?@foo.bar foo@similarly-long-address-url.of-253-characters.long.which-is-still-allowed.within-the-standards.so-lets-just-fill-the-rest.of-this-253-character-long-address-with-lorem-ipsum.copypasta-filler-then.Lorem-ipsum-dolor-sit-amet.consectetur-adipiscing-elit.com foo@similarly-long-address-urls.of-254-characters.long.which-is-not-allowed.within-the-standards.so-lets-just-fill-the-rest.of-this-254-character-long-address-with-lorem-ipsum.copy-pasta-fillers-then.Lorem-ipsum-dolor-sit-amet.consectetur-adipiscing-elit.com"; // 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/