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

/
/
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)^\s*([^#][\w\d_-]+?)\[([\w\d_-]+?)]\s*=\s*(\d+[\.,]\d+)\s*$").unwrap(); let string = "; This is a sample configuration file ; Comments start with ';', as in php.ini [first_section] one = 1 one = 3 one-two = 4 one_three = 3 five = 5.2 animal = BIRD [first_section] second_section[one] = \"1 associated\" second_section[two] = \"2 associated\" second_section[] = \"1 unassociated\" second_section[] = \"2 unassociated\" second_section[] = 1 second_section[] = 1,3 second_section[] = 2,2 [second_section] path = \"/usr/local/bin\" URL = \"http://www.example.com/~username\" second_section[one] = \"1 associated\" second_section[two] = \"2 associated\" second_section[three] = 3 second_section[four] = 4.4 second_section[] = \"1 unassociated\" second_section[] = \"2 unassociated\" second_section[] = 1 second_section[] = 2.2 [third_section] phpversion[] = \"5.0\" phpversion[] = \"5.1\" phpversion[] = \"5.2\" phpversion[] = \"5.3\""; // 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/