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

/
/

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#"air_temp": \K[\d.]+"#).unwrap(); let string = " { \"observations\": { \"notice\": [ { \"copyright\": \"Copyright Commonwealth of Australia 2017, Bureau of Meteorology. For more information see: http://www.bom.gov.au/other/copyright.shtml http://www.bom.gov.au/other/disclaimer.shtml\", \"copyright_url\": \"http://www.bom.gov.au/other/copyright.shtml\", \"disclaimer_url\": \"http://www.bom.gov.au/other/disclaimer.shtml\", \"feedback_url\": \"http://www.bom.gov.au/other/feedback\" } ], \"header\": [ { \"refresh_message\": \"Issued at 12:11 pm EST Tuesday 11 July 2017\", \"ID\": \"IDN60901\", \"main_ID\": \"IDN60902\", \"name\": \"Canberra\", \"state_time_zone\": \"NSW\", \"time_zone\": \"EST\", \"product_name\": \"Capital City Observations\", \"state\": \"Aust Capital Territory\" } ], \"data\": [ { \"sort_order\": 0, \"wmo\": 94926, \"name\": \"Canberra\", \"history_product\": \"IDN60903\", \"local_date_time\": \"11/12:00pm\", \"local_date_time_full\": \"20170711120000\", \"aifstime_utc\": \"20170711020000\", \"lat\": -35.3, \"lon\": 149.2, \"apparent_t\": 5.7, \"cloud\": \"Mostly clear\", \"cloud_base_m\": 1050, \"cloud_oktas\": 1, \"cloud_type_id\": 8, \"cloud_type\": \"Cumulus\", \"delta_t\": 3.6, \"gust_kmh\": 11, \"gust_kt\": 6, \"air_temp\": 9.0, \"dewpt\": 0.2, \"press\": 1032.7, \"press_qnh\": 1031.3, \"press_msl\": 1032.7, \"press_tend\": \"-\", \"rain_trace\": \"0.0\", \"rel_hum\": 54, \"sea_state\": \"-\", \"swell_dir_worded\": \"-\", \"swell_height\": null, \"swell_period\": null, \"vis_km\": \"10\", \"weather\": \"-\", \"wind_dir\": \"WNW\", \"wind_spd_kmh\": 7, \"wind_spd_kt\": 4 }, { \"sort_order\": 1, \"wmo\": 94926, \"name\": \"Canberra\", \"history_product\": \"IDN60903\", \"local_date_time\": \"11/11:30am\", \"local_date_time_full\": \"20170711113000\", \"aifstime_utc\": \"20170711013000\", \"lat\": -35.3, \"lon\": 149.2, \"apparent_t\": 4.6, \"cloud\": \"Mostly clear\", \"cloud_base_m\": 900, \"cloud_oktas\": 1, \"cloud_type_id\": 8, \"cloud_type\": \"Cumulus\", \"delta_t\": 2.9, \"gust_kmh\": 9, \"gust_kt\": 5, \"air_temp\": 7.3, \"dewpt\": 0.1, \"press\": 1033.1, \"press_qnh\": 1031.7, \"press_msl\": 1033.1, \"press_tend\": \"-\", \"rain_trace\": \"0.0\", \"rel_hum\": 60, \"sea_state\": \"-\", \"swell_dir_worded\": \"-\", \"swell_height\": null, \"swell_period\": null, \"vis_km\": \"10\", \"weather\": \"-\", \"wind_dir\": \"NW\", \"wind_spd_kmh\": 4, \"wind_spd_kt\": 2 } ] } }"; // result will be a tuple containing the start and end indices for the first match in the string let result = regex.captures(string); let (start, end) = match result { Some((s, e)) => (s, e), None => { // ... } }; println!("{}", &string[start, end]); }

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/