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

/
/
xg

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#"(?x)(?(DEFINE) (?<number> (?>-? (?= [1-9]|0(?!\d) ) \d+ (\.\d+)? ([eE] [+-]? \d+)?) ) (?<boolean> (?> true | false | null )) (?<unquoted> (?> ([^"\\]* | \\ ["\\bfnrt\/] | \\ u [0-9a-f]{4} )* )) (?<string> (?>" (?&unquoted) " )) (?<array> (?> \[ (?: (?&json) (?: , (?&json) )* )? \s* \] )) (?<pair> (?> \s* (?&string) \s* : (?&json) )) (?<object> (?>\{ (?: (?&pair) (?: , (?&pair) )* )? \s* \} )) (?<json> (?>\s* (?: (?&number) | (?&boolean) | (?&string) | (?&array) | (?&object) ) \s* )) ) (?<=") # Lookbehind for quote before parent key string (?&unquoted) # parent key string (?= # Lookahead for object properties including unique property marker "\s*:\s*{\s* (?: (?&pair) (?: , (?&pair) )* )? # any number of property key value pairs, optional. (?:(?:\s* , )?\s* "type"\s*:\s*"title") # unique property marker, optionally perfixed with comma. (?: \s*, (?&pair) )* # any number of property key value pairs, optional. \s*} )"#).unwrap(); let string = " .. \"id\": \"Xkt@\", \"name\": \"My Email\", \"type\": \"email\" }, \"Item of Equipment\": { \"id\": \"title\", \"title\": {}, \"name\": \"Item of Equipment\", \"type\": \"title\" }, \"My Date\": { \"id\": \"nYcK\", \"name\": \"My Date\", \"type\": \"date\", .. \"Item of Equipment\": { \"type\": \"title\", \"id\": \"title\", \"title\": {}, \"name\": \"Item of Equipment\" },"; // 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/