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"((?:[A-Z-][ ]){9,}[A-Z])\s+([A-Z \n',.-]+)\b(?![A-Z]+(?=\.))\b(?![a-z']|[A-Z.])(.*?)(?=(?:[A-Z][ ]){9,}|This book \n)", flags=re.DOTALL) test_str = ("This is some introduction text.\n\n" "Here's the table of contents:\n\n" "ONE \n\n" "The Boy Who Lived · 1 \n" "TWO \n\n" "The Vanishing Glass · 18 \n" "THREE \n\n" "The Letters from No One · 31 \n\n" "FOUR \n\n" "The Keeper of the Keys · 46 \n\n" "C H A P T E R O N E \n\n\n\n\n" "THE BOY WHO LIVED \n\n" "Mr. and Mrs. Dursley, and their greatest fear was that somebody would discover it. \n" "• 1 • \n\n" "CHAPTER ONE He couldn’t know that at this very moment, people meeting in secret all over the country were holding up their glasses and saying in hushed voices: “To Harry Potter — the boy who lived!” \n" "• 17 • \n\n\n\n" "C H A P T E R E X A M P L E\n\n\n\n" "IT'S A NEW CHAPTER\n\n" "WITH. SEVERAL, EDGE-CASES\n\n" "EDGECASE. The chapter continues...\n\n" "C H A P T E R T W O \n\n\n\n\n" "THE VANISHING GLASS \n\n" "Nearly ten years had passed since the Dursleys Everybody knew that Dudley’s gang hated that odd Harry Potter in his baggy old clothes and broken glasses, and nobody liked to disagree with Dudley’s gang. \n" "• 30 • \n\n" "C H A P T E R T H R E E \n\n\n" "THE LETTERS \n\n\n\n" "FROM NO ONE \n\n" "The escape of the Brazilian boa constrictor earned with Dudley this summer. . . .” \n" "• 309 • \n\n" "This book \n" "was art directed by \n" "David Saylor and designed by Becky \n" "Terhune. The art for both the jacket and interior was \n" "created using pastels on toned printmaking paper. The text was \n" "set in 12-point Adobe Garamond, a typeface based on the sixteenth- \n" "century type designs of Claude Garamond redrawn by Robert \n" "Slimbach in 1989. The book was printed and bound \n" "at RR Donnelley & Sons, Willard, Oh. \n" "The production was supervised by \n" "Angela Biola \n\n\n\n\n\n\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