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"
"
gmi

Test String

Code Generator

Language

Generated Code

use strict; my $str = ' 70 02 [95386.467810]= 50 MiB 28414 (1806 ms in 2 ms) in 5 ms 2.74GHz 434MHz 90kHz 23Hz 1.7k 2 ul 07 [2484867] 41666 KiB/s 29107 [17755556] 0s [ | 2.74 GHz 434 MHz 90 KHz 45 kHz 23 Hz [143M 8317 (-70831 us) 10023ms ()-> 10022ms ( (37.9 kHz e) 0.389978] pci 4ns 1.4M 9986 [100k Sep-22] 468G 163G 282G 3 511M 5.3M 506M 5.5T 4.3T 1.3T 1.2T 890M 236G -l 1.1T 17G ) 3.4T c 1.1T 1.7T cinema 15G software 446G software 5.5T total 29k x 4 4.1k 23-Sr 4.1k 2 r 4.1k 1 4.1k :38 5 ter 4.1k r 4.1k st 23-Feb "2022-09-21T00:49:08.191147376+03:00"p4* 2% /boot/efi @ 192.168.1.2 :/mnt/6Sep (0) g 02:45:46 done 600 601 605 628 +h 00:48:22  0312./05 III (2020-2021) 1'; my $regex = qr/(?<=[\s\b()-])(\d+)(\.\d+)?(?=\s?[A-Za-z]?)((\s?[kmgtpun])?(i?b/?s?|s|hz)?)(?=[]\s\b()[]|$)/mip; if ( $str =~ /$regex/g ) { print "Whole match is ${^MATCH} and its start/end positions can be obtained via \$-[0] and \$+[0]\n"; # print "Capture Group 1 is $1 and its start/end positions can be obtained via \$-[1] and \$+[1]\n"; # print "Capture Group 2 is $2 ... and so on\n"; } # ${^POSTMATCH} and ${^PREMATCH} are also available with the use of '/p' # Named capture groups can be called via $+{name}

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 Perl, please visit: http://perldoc.perl.org/perlre.html