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

Substitution

Processing...

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)(?:(?=(?&V_Obj)){|(?!^)\G(?&Sep_Obj)\s*)(?:(?&V_KeyVal)(?&Sep_Obj))*?\s*(?&Str)\s*:\s*\K(?&Numb)(?(DEFINE)(?<Sep_Ary>\s*(?:,(?!\s*[}\]])|(?=\])))(?<Sep_Obj>\s*(?:,(?!\s*[}\]])|(?=})))(?<Er_Obj>(?>{(?:\s*(?&Str)(?:\s*:(?:\s*(?:(?&Er_Value)|(?<Er_Ary>\[(?:\s*(?:(?&Er_Value)|(?&Er_Ary)|(?&Er_Obj))(?:(?&Sep_Ary)|(*ACCEPT)))*(?:\s*\]|(*ACCEPT)))|(?&Er_Obj))(?:(?&Sep_Obj)|(*ACCEPT))|(*ACCEPT))|(*ACCEPT)))*(?:\s*}|(*ACCEPT))))(?<Er_Value>(?>(?&Numb)|(?>true|false|null)|(?&Str)))(?<Str>(?>"[^\\"]*(?:\\[\s\S][^\\"]*)*"))(?<Numb>(?>[+-]?(?:\d+(?:\.\d*)?|\.\d+)(?:[eE][+-]?\d+)?|(?:[eE][+-]?\d+)))(?<V_KeyVal>(?>\s*(?&Str)\s*:\s*(?&V_Value)\s*))(?<V_Value>(?>(?&Numb)|(?>true|false|null)|(?&Str)|(?&V_Obj)|(?&V_Ary)))(?<V_Ary>\[(?>\s*(?&V_Value)(?&Sep_Ary))*\s*\])(?<V_Obj>{(?>(?&V_KeyVal)(?&Sep_Obj))*\s*}))"#).unwrap(); let string = "{ \"first_name\":\"sample\", \"last_name\": \"lastname\", \"integer\" : 100, \"float\" : 1555.20, \"createddate\":\"2015-06-25 09:57:28\", \"asder\" : [ 200, 100, { \"nother1\" : \"here\", \"digi1\" : 900e10, \"nother1\" : \"here\", \"digi2\" : 3.14 }, 400, 37 ] }"; let substitution = "\"$0\""; // result will be a String with the substituted value let result = regex.replace_all(string, substitution); println!("{}", result); }

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/