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

r"
"
gm

Test String

Code Generator

Language

Generated Code

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @"^(?P<LogTime>[A-Za-z0-9 :]+)\s(?P<Hostname>[a-z0-9.-]+)\s(?:ae_(?P<EnvIdentity>[a-z-]+):)\s(?P<ModuleName>[a-zA-Z._]+)?\s-\s(?P<LogLevel>[A-Z]+)\s-\s(?:\[JID:(gen:)?(?P<TaskId>[a-z0-9-]+)\]\s?)?(?:\[FID:(?P<FieldId>[a-z0-9-]+)\]\s?)?(?:\[Itin:(?P<Itinerary>[A-Za-z0-9]+)(?:->(?P<Step>[A-Z0-9a-z]+))?\]\s?)?(?:\[State:(?P<State>[A-Za-z]+)\]\s?)?(?:alias=(?P<StepAlias>[a-z0-9]+),\s)?(?:runtime_s=\[?(?P<JobRuntimeSeconds>[0-9.]+)\]?\s?)?(?:metadata=(?P<Metadata>{.*}))?$"; string input = @"Oct 30 09:54:06 production-ae-workers-d8c35 ae_env-name: ae.core.manager - INFO - [JID:gen:156364bc-fb25-11e9-8d15-02420af40b07] [FID:dead-f4rm-dead] [Itin:RunFieldForecastHourlyUpdate] [State:Finished] runtime_s=[16.03] metadata={""initiating_event"": ""hourly"", ""hourly_timestamp"": ""2019/10/30/14/00"", ""timestamp"": ""2019/10/30/08/00"", ""pd_meta"": {""farm"": {""uuid"": ""dead-beef-dead"", ""name"": ""My Farm Name""}, ""field"": {""uuid"": ""dead-b00b-dead"", ""name"": ""My house""}, ""token"": ""REDACTED"", ""organization"": {""uuid"": ""dead-f00d-dead"", ""name"": ""My Organization""}, ""enterprise_group"": {""uuid"": ""dead-gr0up-dead"", ""name"": ""My Group""}}, ""field_uuid"": ""dead-f4rm-dead"", ""token"": ""REDACTED"", ""process_cfs"": false, ""seed_corn"": false, ""current_cropping"": null, ""daily_timestamp"": ""2019/10/30/08/00"", ""ye_target"": ""user"", ""priority"": 3}"; RegexOptions options = RegexOptions.Multiline; foreach (Match m in Regex.Matches(input, pattern, options)) { Console.WriteLine("'{0}' found at index {1}.", m.Value, m.Index); } } }

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 C#, please visit: https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex(v=vs.110).aspx