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#"(\<meta([\s]*(name="viewport"){1})[\w\d\s\.\-,=]*(content="){1}[\w\d\s\.\-,=]*(viewport-fit=cover){1}[\w\d\s\.\-,="]+\/\>)"#).unwrap(); let string = "<!DOCTYPE html> <html lang=\"en\"> <head> <meta charset=\"utf-8\" /> <title>Ionic App</title> <base href=\"/\" /> <!-- viewport-fit on multiline meta --> <meta name=\"viewport\" content=\"viewport-fit=cover, width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no\" /> <meta name=\"viewport\" content=\"viewport-fit=cover, width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no\" /> <meta name=\"viewport\" content=\"viewport-fit=cover, width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no\" /> <!-- viewport-fit on singleline content at the start --> <meta name=\"viewport\" content=\"viewport-fit=cover, width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no\" /> <!-- viewport-fit on singleline content at the end --> <meta name=\"viewport\" content=\"width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no, viewport-fit=cover\" /> <meta name=\"format-detection\" content=\"telephone=no\" /> <meta name=\"msapplication-tap-highlight\" content=\"no\" /> <link rel=\"icon\" href=\"assets/icon/favicon.ico\" /> <!-- add to homescreen for ios --> <meta name=\"apple-mobile-web-app-capable\" content=\"yes\" /> <meta name=\"apple-mobile-web-app-status-bar-style\" content=\"black\" /> </head> <body> <app-root></app-root> </body> </html> "; // 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/