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"^(?=.*[BFGJKPQVWXYZ])\w{3}\b" test_str = ("THE 53097401461\n" "OF 30966074232\n" "AND 22632024504\n" "TO 19347398077\n" "IN 16891065263\n" "A 15310087895\n" "IS 8384246685\n" "THAT 8000768228\n" "FOR 6545282031\n" "IT 5740085369\n" "AS 5700645258\n" "WAS 5502713968\n" "WITH 5182797249\n" "BE 4818864785\n" "BY 4703106084\n" "ON 4594521081\n" "NOT 4522732626\n" "HE 4110457083\n" "I 3884828634\n" "THIS 3826060334\n" "ARE 3700433333\n" "OR 3667713965\n" "HIS 3611377789\n" "FROM 3469207674\n" "AT 3413452256\n" "WHICH 3140226612\n" "BUT 2792350185\n" "HAVE 2777439117\n" "AN 2726250863\n" "HAD 2616021603\n" "THEY 2462131290\n" "YOU 2337737641\n" "WERE 2270487439\n" "THEIR 2152980325\n" "ONE 2148983086\n" "ALL 2062779102\n" "WE 2057296224") 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