Regular Expressions 101

Save & Share

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8
  • .NET 7.0 (C#)
  • Rust
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests

Tools

Sponsors
There are currently no sponsors. Become a sponsor today!
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

$re = '/(?P<hit_count>"hit_count"\s*:\s*"\{\\\\\"(?P<group_by>[^\\\\\"]+)\\\\\":\{(?:\\\\\"([^\\\\\"]+)\\\\\":([0-9]+))?(?:,\\\\\"([^\\\\\"]+)\\\\\":([0-9]+))?(?:,\\\\\"([^\\\\\"]+)\\\\\":([0-9]+))?(?:,\\\\\"([^\\\\\"]+)\\\\\":([0-9]+))?(?:,\\\\\"([^\\\\\"]+)\\\\\":([0-9]+))?(?:,\\\\\"([^\\\\\"]+)\\\\\":([0-9]+))?\}\}")/m'; $str = '{"integration_text":"A Coralogix alert has been triggered!","alert_url":"https://Medigate.coralogix.com/#/insights?id=00270770-5eed-11eb-91d9-fd643179e246","alert_subsystem":"Multiple Subsystems","alert_severity":"INFO","alert_id":"3f99f720-5afe-11eb-94ee-09d1be14b22b","alert_application":"Multiple Applications","hit_count":"{\\"host.hostname\\":{\\"ksbl-liestal-collection-laufen\\":27,\\"quiron-hev-collection\\":27,\\"klinikumdo-main-collection\\":16,\\"zgks-zug-collection\\":1}}","alert_name":"Medparser KA"} {"integration_text":"A Coralogix alert has been triggered!","alert_url":"https://Medigate.coralogix.com/#/insights?id=cc3da9c0-5eef-11eb-8c43-5b48837995a8","alert_subsystem":"Multiple Subsystems","alert_severity":"INFO","alert_id":"7097bde0-5b0c-11eb-8a52-29a11019991e","alert_application":"Multiple Applications","hit_count":"{\\"host.hostname\\":{\\"chtourcoing-main-analysis\\":6,\\"mannheimu-main-analysis\\":6,\\"clalit-soroka-analysis\\":5,\\"maastrichtu-main-analysis\\":5,\\"ntu-taipei-analysis\\":5}}","alert_name":"Medalert Activity KA"} '; $subst = "$1,\"hit_count_object\":{\"group_by\":\"$2\",\"hits\":[{\"key\":\"$3\",\"count\":$4},{\"key\":\"$5\",\"count\":$6},{\"key\":\"$7\",\"count\":$8},{\"key\":\"$9\",\"count\":$10},{\"key\":\"$11\",\"count\":$12}]}"; $result = preg_replace($re, $subst, $str); echo "The result of the substitution is ".$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 PHP, please visit: http://php.net/manual/en/ref.pcre.php