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)"resource_id": "[^"]*?(?<last_word>\w+)""#).unwrap(); let string = "{\"resource_id\": \"/subscriptions/85bbb6fe-yyyy-xxx-81a6-806aaa0ca/resourceGroups/vg-test/providers/Microsoft.Web/sites/TestAPI\", \"metric_name\": \"FSUsage\", \"timeStamp\": \"2025-12-14T14:48:00Z\", \"subscription_id\": \"85bbb6fe-yyyy-xxx-81a6-806aaa0ca\", \"unit\": \"Bytes\", \"namespace\": \"microsoft.web/sites\", \"resource_group\": \"vg-test\", \"average\": 0} {\"resource_id\": \"/subscriptions/85bbb6fe-yyyy-xxx-81a6-806aaa0ca/resourceGroups/vg-test/providers/Microsoft.Sql/servers/test-sql-01/databases/Test_Prod\", \"metric_name\": \"allocated_storage\", \"timeStamp\": \"2025-12-14T14:57:00Z\", \"subscription_id\": \"85bbb6fe-yyyy-xxx-81a6-806aaa0ca\", \"unit\": \"Bytes\", \"namespace\": \"microsoft.sql/databases\", \"resource_group\": \"vg-test\", \"average\": 855016}"; // 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/