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

/
/

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"^([a-zA-Z0-9_=]+)\.([a-zA-Z0-9_=]+)\.([a-zA-Z0-9_\-\+\/=]*)").unwrap(); let string = "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJncm91cCI6ImFuZHJvaWQiLCJhdWQiOiJhbmRyb2lkIiwiaXNzIjoiYXBpLnNvY2lhbGRlYWwubmwiLCJtZW1iZXIiOnsibmFtZSI6ImVyaWsifSwiZXhwIjoxNDUyMDgzMjA3LCJpYXQiOjE0NTE5OTY4MDd9.u7ZBa9RB8U4QL8eBk4hmsjg8oFW19AHuen12c8CvLMj0IQUsNqeC-vwNQvAINpgBM0bzDf5cotyrUzf55eXch6mzfKMa-OJXguO-lARp4fc40HaBWbfnEvGe7yEgSESkt6gJNuprG51A6f4AJyNlXG_3u7O4bAMwiPZJc3AAU84_JXC7Vlq1X3FMaLVGmZdxzA4TvYZEiTt_KHoA49UgzeZtNXo3YiDq-GgL1eV8Li01fwy-M--xzbp4cPcY89jkPyYxUIJEoITOULr3zXQwRfYVe6i0P28oyu5ZzAwYCajBb2T98zN7sFJarNmtcxSKNfhCPnMVn3wrpxx4_Kd2Pw"; // 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/