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"^(\w{3}\s{1}\w{3}\s{1}\d{2}\s{1}\d{2}\:\d{2}\:\d{2}\s{1}\d{4})?((\r||.|\n)*)(?=(\w{3}\s{1}\w{3}\s{1}\d{2}\s{1}\d{2}\:\d{2}\:\d{2}\s{1}\d{4}))" test_str = ("Tue Sep 14 08:57:47 2021\n" "Thread 1 advanced to log sequence 186 (LGWR switch)\n" " Current log# 2 seq# 186 mem# 0: D:\\ORADB\\DV1\\REDO02A.LOG\n" " Current log# 2 seq# 186 mem# 1: H:\\ORADB\\DV1\\REDO02B.LOG\n" "Tue Sep 14 09:07:40 2021\n" "Thread 1 advanced to log sequence 187 (LGWR switch)\n" " Current log# 3 seq# 187 mem# 0: D:\\ORADB\\DV1\\REDO03A.LOG\n" " Current log# 3 seq# 187 mem# 1: H:\\ORADB\\DV1\\REDO03B.LOG\n" "Tue Sep 14 09:22:09 2021\n" "Thread 1 advanced to log sequence 188 (LGWR switch)\n" " Current log# 4 seq# 188 mem# 0: D:\\ORADB\\DV1\\REDO04A.LOG\n" " Current log# 4 seq# 188 mem# 1: H:\\ORADB\\DV1\\REDO04B.LOG\n" "Tue Sep 14 09:38:03 2021\n" "Thread 1 advanced to log sequence 189 (LGWR switch)\n" " Current log# 1 seq# 189 mem# 0: D:\\ORADB\\DV1\\REDO01A.LOG\n" " Current log# 1 seq# 189 mem# 1: H:\\ORADB\\DV1\\REDO01B.LOG") 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