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

/
/
ixgm

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#"(?ixm)(?(DEFINE) (?<number> -? (?= [1-9]|0(?!\d) ) \d+ (\.\d+)? ([eE] [+-]? \d+)? ) (?<boolean> true | false | null ) (?<string> " ([^"\\\\]* | \\\\ ["\\\\bfnrt\/] | \\\\ u [0-9a-f]{4} )* " ) (?<array> \[ (?: (?&json) (?: , (?&json) )* )? \s* \] ) (?<pair> \s* (?&string) \s* : (?&json) ) (?<object> \{ (?: (?&pair) (?: , (?&pair) )* )? \s* \} ) (?<fieldname> [a-zA-Z0-9\_\-]+ ) (?<json> \s* (?: (?&number) | (?&boolean) | (?&string) | (?&array) | (?&object) ) ) (?<fieldlist> (?: (?&fieldname) (?: , (?&fieldname) )+ )+ ) ) (?'actiontag' \@(?&fieldname) ) (?:\= (?'params' (?: (?'match_list'(?&fieldlist)) | (?'match_json'(?&json)) | (?'match_string'(?:[[:alnum:]_-]+)) ) ) )?"#).unwrap(); let string = "@tag=1,2,3 @b=asdferf @tag=a,1,b,foo_123,asf @tag=a,b,c @A_S:-DF=foo @ABC={\"f\":{\"A\":\"b\"}} @A=[ {\"a\":\"b\"}, {\"C\":\"D\"} ] @B @A={\"a\":\"b\"} @ASDF={ \"foo\":\"bar\", \"fdsa\":\"fdsa\" } @ASDF=FOO FOO=ASD @ASDFFADS={\"ASDF\":\"fdsa\"} @ASDF{\"asdf\":\"asdf\"} @ASDF=\"This is a place holder\" @FDSA=\"James Brown\" @D=Fing poo @FEE @BOO @IMAGE_TAG=FOO @IMAGE-tag=ASDF2 @ASDF={\"foo\":\"bar\"} FOO=ASDF @ASDFFADS={\"ASDF\":\"fdsa\"} @t3={ \"glossary\": { \"title\": \"example glossary\", \"GlossDiv\": { \"title\": \"S\", \"GlossList\": { \"GlossEntry\": { \"ID\": \"SGML\", \"SortAs\": \"SGML\", \"GlossTerm\": \"Standard Generalized Markup Language\", \"Acronym\": \"SGML\", \"Abbrev\": \"ISO 8879:1986\", \"GlossDef\": { \"para\": \"A meta-markup language, used to create markup languages such as DocBook.\", \"GlossSeeAlso\": [ \"GML\", \"XML\" ] }, \"GlossSee\": \"markup\" } } } } }"; // 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/