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 = '2018-12-07T14:41:55.974-0500: 358622.986: [SoftReference, 101571 refs, 0.0364703 secs]2018-12-07T14:41:56.010-0500: 358623.023: [WeakReference, 70294 refs, 0.0118371 secs]2018-12-07T14:41:56.022-0500: 358623.035: [FinalReference, 3823 refs, 0.0020774 secs]2018-12-07T14:41:56.024-0500: 358623.037: [PhantomReference, 271 refs, 993 refs, 0.0002618 secs]2018-12-07T14:41:56.024-0500: 358623.037: [BRU Weak Reference, 0.0008795 secs] 17G->12G(18G), 29.3445337 secs] [Eden: 0.0B(920.0M)->0.0B(3408.0M) Survivors: 0.0B->0.0B Heap: 17.7G(18.0G)->12.4G(18.0G)], [Metaspace: 683138K->682699K(1738752K)] [Times: user=56.84 sys=0.00, real=29.35 secs]'; my $regex = qr/BRU Weak Reference,[^,]+,\s+(?<bru_weak_reference>[^\s]+)/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