Regular Expressions 101

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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

Code Generator

Language

Generated Code

use strict; my $str = ' atggagga gccgcagtca gatcctagcg tcgagccccc 241 tctgagtcag gaaacatttt cagacctatg gaaactactt cctgaaaaca acgttctgtc 301 ccccttgccg tcccaagcaa tggatgattt gatgctgtcc ccggacgata ttgaacaatg 361 gttcactgaa gacccaggtc cagatgaagc tcccagaatg ccagaggctg ctccccccgt 421 ggcccctgca ccagcagctc ctacaccggc ggcccctgca ccagccccct cctggcccct 481 gtcatcttct gtcccttccc agaaaaccta ccagggcagc tacggtttcc gtctgggctt 541 cttgcattct gggacagcca agtctgtgac ttgcacgtac tcccctgccc tcaacaagat 601 gttttgccaa ctggccaaga cctgccctgt gcagctgtgg gttgattcca cacccccgcc 661 cggcacccgc gtccgcgcca tggccatcta caagcagtca cagcacatga cggaggttgt 721 gaggcgctgc ccccaccatg agcgctgctc agatagcgat ggtctggccc ctcctcagca 781 tcttatccga gtggaaggaa atttgcgtgt ggagtatttg gatgacagaa acacttttcg 841 acatagtgtg gtggtgccct atgagccgcc tgaggttggc tctgactgta ccaccatcca 901 ctacaactac atgtgtaaca gttcctgcat gggcggcatg aaccggaggc ccatcctcac 961 catcatcaca ctggaagact ccagtggtaa tctactggga cggaacagct ttgaggtgcg 1021 tgtttgtgcc tgtcctggga gagaccggcg cacagaggaa gagaatctcc gcaagaaagg 1081 ggagcctcac cacgagctgc ccccagggag cactaagcga gcactgccca acaacaccag 1141 ctcctctccc cagccaaaga agaaaccact ggatggagaa tatttcaccc ttcagatccg 1201 tgggcgtgag cgcttcgaga tgttccgaga gctgaatgag gccttggaac tcaaggatgc 1261 ccaggctggg aaggagccag gggggagcag ggctcactcc agccacctga agtccaaaaa 1321 gggtcagtct acctcccgcc ataaaaaact catgttcaag acagaagggc ctgactcaga 1381 ctga'; my $regex = qr/\A(?:(?:[\s\d]*[acgt]){3}){247}\K(?:[\s\d]*[acgt]){3}/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