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"(?<=url=tcp://)[1-9][0-9]?\.tcp\.(?:ap|au|eu|in|jp|sa|us)\.ngrok\.io:[1-9][0-9]{4}\b" test_str = ("t=2023-07-05T16:17:15+0300 lvl=info msg=\"no configuration paths supplied\"\n" "t=2023-07-05T16:17:15+0300 lvl=info msg=\"using configuration at default config path\" path=C:\\\\Users\\\\***\\\\AppData\\\\Local/ngrok/ngrok.yml\n" "t=2023-07-05T16:17:15+0300 lvl=info msg=\"open config file\" path=C:\\\\Users\\\\***\\\\AppData\\\\Local\\\\ngrok\\\\ngrok.yml err=nil\n" "t=2023-07-05T16:17:15+0300 lvl=info msg=\"starting web service\" obj=web addr=127.0.0.1:4040 allow_hosts=[]\n" "t=2023-07-05T16:17:15+0300 lvl=info msg=\"tunnel session started\" obj=tunnels.session\n" "t=2023-07-05T16:17:15+0300 lvl=info msg=\"client session established\" obj=csess\n" "t=2023-07-05T16:17:15+0300 lvl=info msg=\"started tunnel\" obj=tunnels name=command_line addr=//localhost:8865 url=tcp://4.tcp.eu.ngrok.io:10355\n" "t=2023-07-05T16:17:16+0300 lvl=info msg=\"update available\" obj=updater") 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