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

r"
"
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"(?m)^(\d\.?[\d.]*? ?[ \-,:\w]+) ?\r?$" test_str = ("5.2 Marking this is a heading\n" "All relevant information, as detailed in 5.1, which is to be marked on the equipment, shall be\n" "specified in the relevant product standard.\n" "Markings shall be indelible and easily legible.\n" "Marking of the manufacturer's name or trademark and type designation or serial number is\n" "mandatory on the equipment and preferably on the nameplate, if any, in order to permit the\n" "----------------------------------------------------------------------------------\n" "MARKING this is a heading\n" "70 General this is a subheading\n\n" "70.1 Industrial control equipment shall be plainly marked with: this is a heading\n" "a) The manufacturer’s name, trademark, or other descriptive marking by which the organization\n" "responsible for the product may be identified – hereinafter referred to as the manufacturer’s\n" "name;\n" "---------------------------------------------------------------------------------\n" "9 Marking this is a heading\n\n" "Advisory Note: In Canada, there are two official languages, English and French. Annex C lists\n" "acceptable French translations of the markings specified in this standard. All markings required\n" "by this standard may have to be in other languages to conform with the language requirements\n" "where the product is to be used.\n\n" "9.1 General-purpose marking this is a subheading\n" "In addition to the marking required for general-purpose equipment, the minimum marking shall\n" "include the information in 9.2 through 9.11 as applicable. This information shall be readily visible\n\n" "9.1.3 this is also a subheading\n\n" "(?m)^(\\d+\\.\\d+\\s[ \\w,\\-]+)\\r?$ <--- headings\n\n" "(?m)^(\\d\\.[\\d.]+ ?[ \\w]+) ?\\r?$ <--- subheadings\n\n" "(?m)^(\\d\\.?[\\d.]*? ?[ \\-,:\\w]+) ?\\r?$ <--- master") 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