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

Substitution

Processing...

Code Generator

Language

Generated Code

use strict; my $str = ' tests/test_pytest_fold.py::test_1_passes_and_has_logging_output ------------------------------------------------------------------ live log setup ------------------------------------------------------------------ INFO root:test_pytest_fold.py:52 Running test tests.test_pytest_fold... INFO root:test_pytest_fold.py:53 Setting test up... INFO root:test_pytest_fold.py:54 Executing test... INFO root:test_pytest_fold.py:56 Tearing test down... ------------------------------------------------------------------ live log call ------------------------------------------------------------------- CRITICAL root:test_pytest_fold.py:63 Live military happy. View water one land until interesting leader. ERROR root:test_pytest_fold.py:64 Kid expert show cost. Point daughter team attorney keep improve serve. WARNING root:test_pytest_fold.py:65 Arm paper write guess close modern. INFO root:test_pytest_fold.py:66 Recently each rich. DEBUG root:test_pytest_fold.py:67 Attack also do far pressure address hot. PASSED [ 31%] tests/test_pytest_fold.py::test_2_fails_and_has_logging_output ------------------------------------------------------------------ live log setup ------------------------------------------------------------------ INFO root:test_pytest_fold.py:52 Running test tests.test_pytest_fold... INFO root:test_pytest_fold.py:53 Setting test up... INFO root:test_pytest_fold.py:54 Executing test... INFO root:test_pytest_fold.py:56 Tearing test down... ------------------------------------------------------------------ live log call ------------------------------------------------------------------- CRITICAL root:test_pytest_fold.py:72 Paper such fund find international occur good deal. ERROR root:test_pytest_fold.py:73 Today type which situation people nation develop. WARNING root:test_pytest_fold.py:74 Rich key set point answer. Sing Republican continue bar however hundred. INFO root:test_pytest_fold.py:75 Work level century myself piece. Share news no husband cold. Half up send board than current. DEBUG root:test_pytest_fold.py:76 Require matter impact speech left to. FAILED [ 34%] This is giving me a lot of trouble. I\'ve been digging into the more advanced aspects of regex (lookarounds, and more esoteric matching symbols like \\v), but so far my teammates and I haven\'t come up with anything workable. Anyone care to take a stab at it? For the above second code example, I want to match so that I get the following (testname and its outcome): test_1_passes_and_has_logging_output PASSED test_2_fails_and_has_logging_output FAILED'; my $regex = qr~^.*?::(.*?(pass|fail).*)~mp; my $subst = '\\1 \\U\\2ED'; 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