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"^(?!(?!0* 0* 0*|0*+(?=(\d*?)((?:(?=\d+ 0*+(\d*?)(\d(?(4)\4)) 0*(\d*?)(\d\6?+)$)\d)+) )(?=(?(?!\1(?:(?=\d+ 0*\3((\7?+)\d))(?=\d(\d* 0*\3\8))(?=0\9[9]|1\9[8]|2\9[7]|3\9[6]|4\9[5]|5\9[4]|6\9[3]|7\9[2]|8\9[1]|9\9[0])\d)*+(?=\d(\d* 0*\3\8?+))(?=[5-9]\10[5-9]|1\10[9]|2\10[89]|3\10[7-9]|4\10[6-9]|6\10[4]|7\10[34]|8\10[2-4]|9\10[1-4]))(?=\d+ \d+ 0*\1\3\6$)|(?(?!.*+\3)\d+ )(?=\d*(\2|\4)( .*?0*+)\d+$)(?(?=9*\11 )(?:9(?=\d*\12[1](\13?+0)))*(?=\11 )\11\12[1]\13?+\6$|(?:(\d)(?=\d*\12(\15?+\14)))*(?=\d(\d*\12\15?+))(?=0\16[1]|1\16[2]|2\16[3]|3\16[4]|4\16[5]|5\16[6]|6\16[7]|7\16[8]|8\16[9])\d(?:9(?=\d*\12\15?+\d(\17?+0)))*?\11\s)))\1(?:(?=(\d)\d* 0*+\3((\19?+)\d)\d* 0*+\5((\21?+)\d))(?=\d(\d* 0*+\3\20)\d(\d* 0*+\5\22))(?(?!\18(?:(?=\d+ 0*+\3\19((\25?+)\d))(?=\d(\d* 0*+\3\19\26))(?=0\27[9]|1\27[8]|2\27[7]|3\27[6]|4\27[5]|5\27[4]|6\27[3]|7\27[2]|8\27[1]|9\27[0])\d)*+(?=\d(\d* 0*+\3\19\26?+))(?=[5-9]\28[5-9]|1\28[9]|2\28[89]|3\28[7-9]|4\28[6-9]|6\28[4]|7\28[34]|8\28[2-4]|9\28[1-4]))(?=1\23(?:1\24[2]|2\24[3]|3\24[4]|4\24[5]|5\24[6]|6\24[7]|7\24[8]|8\24[9]|9\24[0])|2\23(?:1\24[3]|2\24[4]|3\24[5]|4\24[6]|5\24[7]|6\24[8]|7\24[9]|8\24[0]|9\24[1])|3\23(?:1\24[4]|2\24[5]|3\24[6]|4\24[7]|5\24[8]|6\24[9]|7\24[0]|8\24[1]|9\24[2])|4\23(?:1\24[5]|2\24[6]|3\24[7]|4\24[8]|5\24[9]|6\24[0]|7\24[1]|8\24[2]|9\24[3])|5\23(?:1\24[6]|2\24[7]|3\24[8]|4\24[9]|5\24[0]|6\24[1]|7\24[2]|8\24[3]|9\24[4])|6\23(?:1\24[7]|2\24[8]|3\24[9]|4\24[0]|5\24[1]|6\24[2]|7\24[3]|8\24[4]|9\24[5])|7\23(?:1\24[8]|2\24[9]|3\24[0]|4\24[1]|5\24[2]|6\24[3]|7\24[4]|8\24[5]|9\24[6])|8\23(?:1\24[9]|2\24[0]|3\24[1]|4\24[2]|5\24[3]|6\24[4]|7\24[5]|8\24[6]|9\24[7])|9\23(?:1\24[0]|2\24[1]|3\24[2]|4\24[3]|5\24[4]|6\24[5]|7\24[6]|8\24[7]|9\24[8])|0\23(\d)\24\29|(\d)\23[0]\24\30)|(?=1\23(?:0\24[2]|1\24[3]|2\24[4]|3\24[5]|4\24[6]|5\24[7]|6\24[8]|7\24[9]|8\24[0]|9\24[1])|2\23(?:0\24[3]|1\24[4]|2\24[5]|3\24[6]|4\24[7]|5\24[8]|6\24[9]|7\24[0]|8\24[1]|9\24[2])|3\23(?:0\24[4]|1\24[5]|2\24[6]|3\24[7]|4\24[8]|5\24[9]|6\24[0]|7\24[1]|8\24[2]|9\24[3])|4\23(?:0\24[5]|1\24[6]|2\24[7]|3\24[8]|4\24[9]|5\24[0]|6\24[1]|7\24[2]|8\24[3]|9\24[4])|5\23(?:0\24[6]|1\24[7]|2\24[8]|3\24[9]|4\24[0]|5\24[1]|6\24[2]|7\24[3]|8\24[4]|9\24[5])|6\23(?:0\24[7]|1\24[8]|2\24[9]|3\24[0]|4\24[1]|5\24[2]|6\24[3]|7\24[4]|8\24[5]|9\24[6])|7\23(?:0\24[8]|1\24[9]|2\24[0]|3\24[1]|4\24[2]|5\24[3]|6\24[4]|7\24[5]|8\24[6]|9\24[7])|8\23(?:0\24[9]|1\24[0]|2\24[1]|3\24[2]|4\24[3]|5\24[4]|6\24[5]|7\24[6]|8\24[7]|9\24[8])|9\23(?:0\24[0]|1\24[1]|2\24[2]|3\24[3]|4\24[4]|5\24[5]|6\24[6]|7\24[7]|8\24[8]|9\24[9])|0\23(?:0\24[1]|1\24[2]|2\24[3]|3\24[4]|4\24[5]|5\24[6]|6\24[7]|7\24[8]|8\24[9]|9\24[0])))\d)+\s)).+" test_str = ("0 1 2\n" "10 20 1000\n" "10 20 30\n" "28657 46368 75025\n" "0 0 0\n\n" "8235 49 8284\n" "4 145 149\n" "4705 485 5191\n" "821 75 897\n" "74 497 572\n" "1917 27 1944\n" "89124 3 89128\n" "6858 8669 15527\n" "84916 4 84921\n" "935 63 999\n" "1 9 11\n" "7203 26154 33358\n" "2 765 767\n" "267 8031 8298\n" "2062 188 2251\n" "38 7869 7907\n" "59 85041 85101\n" "705 220 926\n" "71982 2346 74328\n" "9 1 11\n" "3 8117 8120\n" "720 208 928\n" "4 83 88\n" "109 21854 21964\n" "35019 44355 79375\n" "7 9 17\n" "2126 752 2879\n" "2268 53 2321\n" "9 37717 37726\n" "5 949 954") 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