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

Code Generator

Language

Generated Code

# coding=utf8 # the above tag defines encoding for this document and is for Python 2.x compatibility import re regex = r"(?:[a-zA-Z\s]*:)\s*(.*)" test_str = ("Type : Requirement\n" "State : Implemented\n" "Release : 3.1.9 / 3.4.0 *1\n" "The AFTN Message processing shall base on the following external documents:\n" "[ICAO_1] ICAO Annex 10\n" "[ICAO_2] ICAO Doc 4444\n" "[ICAO_3] ICAO Doc 7030\n" "[ICAO_4] ICAO Doc 4444 PANS ATM Amendment No1 *1\n\n\n" "[EURO_1] ADEXP documentation\n" "[EURO_2] IFPS user manual\n\n\n" "[CFMU_1] CFMU_AIC 12.08\n" "[CFMU_2] CFMU 2012 REQUIREMENTS V1.42 *1\n" "[CFMU_3] CFMU INTERFACE MANUAL FOR ICAO 2012 V1.32 *1\n\n\n" "[AIDA_1] ICD FPL AIDA AFPS v40\n\n\n" "[FIXM_1] http://www.fixm.aero/content/fixm-core-releases (FIXM v1.1)\n\n\n" "*1 Due to mutually contradictory between ICAO and CFMU requirements, the documents from CFMU has a higher priority.") matches = re.finditer(regex, test_str, re.MULTILINE) for matchNum, match in enumerate(matches, start=1): print ("Match {matchNum} was found at {start}-{end}: {match}".format(matchNum = matchNum, start = match.start(), end = match.end(), match = match.group())) for groupNum in range(0, len(match.groups())): groupNum = groupNum + 1 print ("Group {groupNum} found at {start}-{end}: {group}".format(groupNum = groupNum, start = match.start(groupNum), end = match.end(groupNum), group = match.group(groupNum))) # Note: for Python 2.7 compatibility, use ur"" to prefix the regex and u"" to prefix the test string and substitution.

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