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

/
/
gmsx

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#"(?msx) # begin capture group 1 \{\s+"name":[ ]" # match '{' then 1+ whitespace chars, then '"name": " (\w+) # match 1+ word chars, save to capture group 1 - # match '-' (\w+) # match 1+ word chars, save to capture group 2 - # match '-' (\w+) # match 1+ word chars, save to capture group 3 - # match '-' (\w+) # match 1+ word chars, save to capture group 4 ( # begin capture group 5 ",\s+"units":[ ] # match '",', then 1+ whitespaces then '"units": ' "\w+" # match 1+ word chars ,\s+"value":[ ] # match ',', then 1+ whitespaces then '"value": ' \d+ # match 1+ digits \s+\} # match 1+ whitespaces then '"units": ' ) # end capture group 5 # end capture group 1 (?! # begin negative lookahead .* # match 0+ chars \{\s+"name":[ ]" # match '{' then 1+ whitespace chars then '"name": ' then '"' \1_ # match contents of capture group 1 then '_' \2_ # match contents of capture group 2 then '_' \3_ # match contents of capture group 3 then '_' \4 # match contents of capture group 4 \5 # match contents of capture group 5 ) # end of negative lookahead | # or \{\s+"name":[ ]" # match '{' then 1+ whitespace chars, then '"name": " \w+ # match 1+ word chars _ # match '_' \w+ # match 1+ word chars _ # match '_' \w+ # match 1+ word chars _ # match '_' \w+ # match 1+ word chars (?5) # execute code constructing capture group 6 "#).unwrap(); let string = "{ \"body\": { \"metricsArray\": [ { \"name\": \"free-aa-bb2-123x123Profiles\", \"units\": \"profiles\", \"value\": 14 }, { \"name\": \"free_aa_bb2_123x123Profiles\", \"units\": \"profiles\", \"value\": 14 } ], \"name\": \"regionxxx\", \"timeStamp\": \"2022-01-20T04:58:29.875Z\" } } "; // 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/