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

use strict; my $str = '100% [Working] 100% [Packages 201 kB] [Waiting for headers] 100% [Waiting for headers] 100% [Packages 201 kB] [Waiting for headers] 100% [Sources 4,444 B] [Waiting for headers] [Waiting for headers] 100% [Packages 39.0 kB] [Waiting for headers] [Waiting for headers] 100% [Translation-en 904 kB] [Waiting for headers] [Waiting for headers] 10% [InRelease gpgv 64.5 kB] [Waiting for headers] [Waiting for headers] [Waiti Reading package lists... 0% Reading package lists... 0% Reading package lists... 1% Reading package lists... 6% 100% [Translation-en 4,149 kB] 17.4 MB/s 0s 100% [Working] 17.4 MB/s 0s 100% [Translation-en 409 kB] 17.4 MB/s 0s 100% [Working] 17.4 MB/s 0s 100% [Translation-en 21.2 kB] 17.4 MB/s 0s 100% [Working] 17.4 MB/s 0s 100% [Translation-en 18.6 MB] 17.4 MB/s 0s 100% [Working] 17.4 MB/s 0s 100% [Working] 100% [Packages 201 kB] [Waiting for headers] 100% [Waiting for headers] Hit http://us.archive.ubuntu.com trusty-backports/multiverse i386 Packages 100% [Working] 100% [Packages 3,341 B] [Waiting for headers] 100% [Waiting for headers] Hit http://us.archive.ubuntu.com trusty-backports/main Translation-en 28% [Sources 507 kB] [1 InRelease 14.2 kB/64.4 kB 22%] [Waiting for headers] [W 28% [Sources 507 kB] [InRelease gpgv 15.4 kB] [1 InRelease 14.2 kB/64.4 kB 22%] 28% [Sources 507 kB] [InRelease gpgv 15.4 kB] [1 InRelease 14.2 kB/64.4 kB 22%] 91% [InRelease gpgv 15.4 kB] [1 InRelease 14.2 kB/64.4 kB 22%] [Waiting for hea 100% [Translation-en 363 kB] [4 Sources 221 kB/250 kB 89%] [Waiting for headers 100% [4 Sources 221 kB/250 kB 89%] [Waiting for headers] [5 Packages 17.0 kB/23'; my $regex = qr/(^(\d+%((?!\r\n)\s+))(\[((\w+)((\-\w+)?((?!\r\n)\s+)?(\w+)?((?!\r\n)\s+)?(\d+)?(\,)?(\d+)?(\.)?(\d?)((?!\r\n)\s+)?(k?B)?)?((?!\r\n)\s+)?(\w+)?\]))?(((((?!\r\n)\s+)\[)(.+)\])*(((?!\r\n)\s+)(\[)(.+))?(\r?\n)))/mp; 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