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
  • 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

/
/
gm

Test String

Substitution

Processing...

Code Generator

Generated Code

use strict; my $str = 'Balanced Quantum Classical Evolutionary Algorithm(BQCEA) Muhammad Shahid, Hasan Mujtaba, Muhammad Asim, Omer Beg Abstract With advancement in Quantum computing, classical algorithms are adapted and integrated with Quantum properties such as qubit representation and entanglement. Although these properties perform better however pre-mature convergence is the main issue in Quantum Evolutionary Algorithms(QEA) because QEA uses only the best individual to update quan- tum population. In this paper, we introduced a new way to update the quantum population of QEA to avoid premature convergence \'Balanced Quantum Classical Evolutionary Algorithm(BQCEA)\\n\\nMuhammad Shahid, Hasan Mujtaba, Muhammad Asim, Omer Beg\\n\\nAbstract\\nWith advancement in Quantum computing, classical algorithms are adapted and integrated\\nwith Quantum properties such as qubit representation and entanglement\', \' Although these\\nproperties perform better however pre-mature convergence is the main issue in Quantum\\nEvolutionary Algorithms(QEA) because QEA uses only the best individual to update quan-\\ntum population\', \' In this paper, we introduced a new way to update the quantum population\\nof QEA to avoid premature convergence\','; my $regex = qr/(?<=\S)(?<!\bAbstract)\n(?=\S)/mp; my $subst = ' '; my $result = $str =~ s/$regex/$subst/rg; print "The result of the substitution is' $result\n";

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