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

/
/
gxm

Test String

Code Generator

Generated Code

# coding=utf8 # the above tag defines encoding for this document and is for Python 2.x compatibility import re regex = r""" \[\ (RUNNING|STOPPED)\ \] (.+?) (?:\[Pid:\ (\d+)\]|$) """ test_str = ("\n\n" "I want to extract the words between the two bracket \"blocks\" and also the word in first brackets (RUNNING or STOPPED).\n\n" "Example (extract the bolded part):\n\n" "[ RUNNING ] My First Application [Pid: 4194]\n\n" "[ RUNNING ] Second app (some data) [Pid: 5248]\n\n" "[ STOPPED ] Logger App\n\n" "So, as you can see, the [Pid: X] part is optional. I can write the regex as follows:\n\n" "\\[\\s+(RUNNING|STOPPED)\\s+\\]\\s+([^\\[]+).*\n\n" "and it will work. But this would fail if App name would contain the '[' character. I tried the following, but it won't work:\n\n" "\\[\\s+(RUNNING|STOPPED)\\s+\\]\\s+(?!\\[Pid)+.*\n\n" "My idea was to match any words/characters that are not starting with \"[Pid\", but I guess this would match any words that are not followed by \"[Pid\".\n\n" "Is there any way to do exactly that: Match any word that is not \"[Pid\", i.e. match the part until first appearing of \"[Pid\" substring?\n") matches = re.finditer(regex, test_str, re.VERBOSE | 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