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
Processing...

Test String

Code Generator

Language

Generated Code

import re regex = re.compile(r"(?x)(?-i:class)\s+[A-Za-z_$][\w$]*\s*\{", flags=re.MULTILINE) test_str = ("class Entity\n" "{\n" " constructor(game,imageURL)\n" " {\n" " this.game = game;\n" " this.sprite = new Sprite(this.game.c,imageURL);\n" " \n" " }\n" " \n" " \n" " draw(depth,offset,textureSize,textureCoordinates,offsetX=0)\n" " {\n" " let scaleFactors = {\n" " 1:1,\n" " 2:0.65,\n" " 3:0.45\n" " };\n" " let scaleFactor = scaleFactors[depth];\n" " \n" " let x = Math.floor(offset.x + textureCoordinates[0] + (textureSize[0] / 2) - (this.sprite.image.width * scaleFactor / 2));\n" " let y = Math.floor(offset.y + textureCoordinates[1] + (textureSize[1] / 2) - (this.sprite.image.height * scaleFactor) + 6 * scaleFactor);\n" " \n" " x = x + offsetX * scaleFactor;\n" " \n" " let width = Math.floor(this.sprite.image.width * scaleFactor);\n" " let height = Math.floor(this.sprite.image.height * scaleFactor);\n" " \n" " let entityFades = {\n" " 1:1,\n" " 2:0.5,\n" " 3:0.1\n" " }\n" " let filter = '';\n" " if(this.game.level.entities.fadeType === 'darken')\n" " {\n" " filter += 'brightness('+entityFades[depth]+')';\n" " }\n" " \n" " this.sprite.draw(\n" " x,\n" " y,\n" " width,\n" " height,\n" " 0,\n" " 0,\n" " this.sprite.image.width,\n" " this.sprite.image.height,\n" " filter\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