Regular Expressions 101

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  • Unit Tests (1)
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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]
  • Character class intersection
    [\w&&[^\d]]
  • 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
Processing...

Test String

Code Generator

Language

Generated Code

import re regex = re.compile(r"^\[Error: +(?<source_path>(?<file>[^\s\n](?:[^\n:\\]+|\\.)+?)(?::(?<line>\d+)(?::(?<column>\d+)))?) *$", flags=re.MULTILINE) test_str = ("/usr/local/lib/node_modules/stylus/bin/stylus:685\n" " throw err;\n" " ^\n\n" "[Error: /Users/user/path/to/stylus/file/invalid.styl:34:5\n" " 30| ==/UserStyle== */\n" " 31| \n" " 32| @-moz-document regexp(\"https?://(www\\\\.)?typescriptlang.org/(v2/)?docs.*$\"),\n" " 33| regexp(\"https?://(www\\\\.)?(staging-)?typescript\\\\.org/docs/.*$\")\n" " 34| error(\"compile error\")\n" "-----------^\n" " 35| \n\n" "compile error\n" "] {\n" " fromStylus: true,\n" " lineno: 34,\n" " column: 5,\n" " filename: '/Users/disk0/git.local/stylus-stylus/static/test/testFiles/invalid.styl',\n" " stylusStack: '',\n" " input: '/* ==UserStyle==\\n' +\n" " '@name TypeScript Docs\\n' +\n" " '@description Expands width of code blocks and moves navigation bar fully to the left\\n' +\n" " '@version 0.0.12\\n' +\n" " '@namespace github.com/disk0/stylus/typescript.org/docs\\n' +\n" " '\\n' +\n" " '@author disk0 (github.com/disco0)\\n' +\n" " '@license MIT\\n' +\n" " '\\n' +\n" " '@preprocessor stylus\\n' +\n" " '\\n' +\n" " '@var select CodeFont \"Font for code displayed on page.\" [\\n' +\n" " ' \"Iosevka Extended*\",\\n' +\n" " ' \"Iosevka Expanded\",\\n' +\n" " ' \"Iosevka Term\",\\n' +\n" " ' \"Iosevka\",\\n' +\n" " '\\n' +\n" " ' \"SemanticHaskell\",\\n' +\n" " ' \"SemanticJavascript\",\\n' +\n" " ' \"SemanticCode\",\\n' +\n" " ' \"Hasklig\",\\n' +\n" " '\\n' +\n" " ' \"PragmataPro Mono Liga\",\\n' +\n" " '\\n' +\n" " ' \"monospace\"\\n' +\n" " ']\\n' +\n" " '@var number CodeFontSize \"Size of code in documentation\" [ 14, 1, 500, 1, \"px\" ]\\n' +\n" " '@var number CodeFontWeight \"Code font weight\" [ 400, 100, 900, 100 ]\\n' +\n" " '@var number DocTextWidth \"Width of text content in documentation\" [ 1000, 300, 5000, 100, \"px\" ]\\n' +\n" " '==/UserStyle== */\\n' +\n" " '\\n' +\n" " '@-moz-document regexp(\"https?://(www\\\\\\\\.)?typescriptlang.org/(v2/)?docs.*$\"),\\n' +\n" " '\\t regexp(\"https?://(www\\\\\\\\.)?(staging-)?typescript\\\\\\\\.org/docs/.*$\")\\n' +\n" " ' error(\"compile error\")\\n'\n" "}\n") matches = regex.finditer(test_str) for match_num, match in enumerate(matches, start=1): print(f"Match {match_num} was found at {match.start()}-{match.end()}: {match.group()}") for group_num, group in enumerate(match.groups(), start=1): print(f"Group {group_num} found at {match.start(group_num)}-{match.end(group_num)}: {group}")

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 Python, please visit: https://docs.python.org/3/library/re.html