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 (1)

Tools

Sponsors
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
  • Match everything enclosed
    (?:...)
  • Capture everything enclosed
    (...)
  • 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

`
`

Test String

Code Generator

Language

Generated Code

using System; using System.Text.RegularExpressions; public class Example { public static void Main() { string pattern = @` ^.+>[\d]\s(?P<Date>\d{4}-\d{2}-\d{2})T(?P<Time>\d{2}:\d{2}:\d{2}).+firewall,info\s(?P<RadUser>\d+).+in:(?P<InputInterface>[^,]+)\s+out:(?P<OutputInterface>[^,]+),\s+(?:src-mac\s+(?P<SourceMacAddress>[^,]+),\s+)?proto\s+(?P<Protocol>\w+)(?:\s+\((?P<Flags>[^)]+)\))?,\s+\[?(?P<SrcIP>\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}|[a-f\d:]+)\]?(?::(?P<SrcPort>\d+))?->\[?(?P<DstIP>\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}|[a-f\d:]+)\]?(?::(?P<DstPort>\d+))?,\s(?P<NAT>\w+)\s\((?P<SrcIpLocalNat>\b(?:\d{1,3}\.){3}\d{1,3}\b):(?P<SrcPortLocalNat>\d+)->(?P<SrcIpPublicNat>\b(?:\d{1,3}\.){3}\d{1,3}\b):(?P<SrcPortPublicNat>\d+)\)->(?P<DestIpNat>\b(?:\d{1,3}\.){3}\d{1,3}\b):(?P<DestPortNat>\d+),.+ `; string input = @"<13>1 2022-05-17T09:10:28.290795-03:00 firewall,info 1727618 - - - 1727618 customlog: in:VLAN99 out:ether2_WAN_Intercorp, src-mac 50:8e:49:7f:b1:68, proto TCP (ACK,FIN), 10.59.0.8:37438->142.251.129.163:443, NAT (10.59.0.8:37438->189.28.49.7:37438)->142.251.129.163:443, len 52 <13>1 2022-05-17T09:18:05.103720-03:00 firewall,info 620254 - - - 620254 customlog: in:VLAN99 out:ether2_WAN_Intercorp, src-mac d0:04:01:8a:ee:7f, proto UDP, 10.59.0.9:42331->172.217.173.110:443, NAT (10.59.0.9:42331->189.28.49.7:42331)->172.217.173.110:443, len 743 "; Match m = Regex.Match(input, pattern); 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