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"^(?=.*g)[fghlotu]{4,}$", flags=re.MULTILINE) test_str = ("// SB from 2019-10-05\n" "// centerLetter: g\n" "// outerLetters: f,h,l,o,t,u\n\n" "// wrong letters\n" "bread\n" "butter\n" "bigger\n" "ogogogx\n" "xogogog\n\n" "// too short\n" "gut\n" "log\n" "fgt\n\n" "// no center letter\n" "trout\n" "lotto\n" "full\n\n" "// tricky cases that should match (made up words)\n" "ogogog\n" "gogog\n" "ogogo\n" "oggoggo\n" "ggogg\n" "ggoo\n" "oogg\n\n" "// actual solutions\n" "thoughtful\n" "flog\n" "fought\n" "fugu\n" "ghoul\n" "glut\n" "golf\n" "goof\n" "googol\n" "goth\n" "gout\n" "guff\n" "gulf\n" "gull\n" "logo\n" "ought\n" "outfought\n" "outgo\n" "outthought\n" "though\n" "thought\n" "thug\n" "tough\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