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

/
/
gm

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"(?m)([\d]*)(.|,)[\d](e|E)[\d]+").unwrap(); let string = "Valid floating points: 1 +1 -1 65 +65 -65 5.2 5,2 5.225 5,225 985.225 985,225 985. ,225 +5.2 +5,2 +5.225 +5,225 +985.225 +985,225 +985. +,225 -5.2 -5,2 -5.225 -5,225 -985.225 -985,225 -985. -,225 5.2E3 5.2e3 +5.2e3 -5.2e3 5,2E3 5,2e3 -5,2e3 +5,2e3 5.2e112 +5.2e112245 -5.2e99999 5,2e112 -5,2e112245 +5,2e99999 5.2e+3 +5.2e+3 -5.2e+3 5,2e-3 -5,2e-3 +5,2e-3 5.e3 5.e+3 +5.e+3 -5.e+3 5,e-3 -5,e-3 +5,e-3 ,225e123 +,225e123 -,225e123 .225e123 +.225e123 -.225e123 Not floating points , , , . . . .e ,e .e2 ,e2 ,225e +,225e -,225e .225e +.225e -.225e"; // 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/