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

/
/
g

Test String

Substitution

Processing...

Code Generator

Language

Generated Code

use strict; my $str = '<h1>TITLE OF HEAD 1</h1> <table> <tbody> <tr> <td class="one">ITEM 1, AFTER HEAD 1</td> </tr> <tr> <td class="one">ITEM 2, AFTER HEAD 1</td> </tr> </tbody> </table> <table> <tbody> <tr> <td class="one">ITEM 3, AFTER HEAD 1</td> </tr> <tr> <td class="one">ITEM 4, AFTER HEAD 1</td> </tr> <tr> <td class="one">ITEM 5, AFTER HEAD 1</td> </tr> </tbody> </table> <h1>TITLE OF HEAD 2</h1> <table> <tbody> <tr> <td class="one">ITEM 6, AFTER HEAD 2</td> </tr> </tbody> </table> <h1>TITLE OF HEAD 3</h1> <table> <tbody> <tr> <td class="one">ITEM 7, AFTER HEAD 3</td> </tr> <tr> <td class="one">ITEM 8, AFTER HEAD 3</td> </tr> <tr> <td class="one">ITEM 9, AFTER HEAD 3</td> </tr> <tr> <td class="one">ITEM 10, AFTER HEAD 3</td> </tr> </tbody> </table> <h1>TITLE OF HEAD 4</h1> <table> <tbody> <tr> <td class="one">ITEM 11, AFTER HEAD 4</td> </tr> <tr> <td class="one">ITEM 12, AFTER HEAD 4</td> </tr> </tbody> </table> '; my $regex = qr/<h1>([^<]*)<\/h1>\s*\n([\w\W]*?)(([^\n\S]*)<td\s.*?<\/td>(\n))(?=\s*<\/tr>)|(?<=<h1>([^<]*)<\/h1>[\w\W]*?)(([^\n\S]*)<td\s.*?<\/td>(\n))(?=\s*<\/tr>)/p; my $subst = '$2$3$4$7$8<td class="two">$1$6</td>$5$9'; 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