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"
"
gm

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"(?m)^_?[a-z0-9]+(?:[._+-][a-z0-9]+)*@(?!\d+(?:\.\d+)*$)(?:\w+(?:-\w+)*\.)+\w{2,}$").unwrap(); let string = "###################### Valid Emails ######################################################## ######################## German, Austrian, international ################################### janedoe@web.de jane.doe@web.de jdoe@web.de jane-doe@web.de jane@web.de doe@web.de janed@web.de doej@web.de jane_doe@web.de j.doe@web.de jane.d@web.de janedoe@t-online.de jane.doe@t-online.de jdoe@t-online.de jane-doe@t-online.de jane@t-online.de janed@t-online.de doej@t-online.de jane_doe@t-online.de j.doe@t-online.de jane.d@t-online.de janedoe@hotmail.de jane.doe@hotmail.de jdoe@hotmail.de jane-doe@hotmail.de janedoe@gmx.de jane.doe@gmx.de jdoe@gmx.de jane-doe@gmx.de jane.doe@post.at jane-doe@post.at janedoe@post.at jane@post.at john.doe@austrian.com horneaudrey@fulbright.at email@example.web ##################################################################################### ########################## Not valid email ########################################## .test@gmail.com -test@gmail.com t.-.est@gmail.com .test.@gmail.com test.@gmail.com test.@.gmail.com test@.gmail.com test@.gmail.com. test@gmail.com. \"email\"@example.com #@%^%#$@#$@#.com @example.com Joe Smith <email@example.com> email.example.com email@example@example.com .email@example.com email.@example.com email..email@example.com あいうえお@example.com email@example.com (Joe Smith) email@example email@-example.com email@111.222.333.44444 email@example..com Abc..123@example.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/