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"^(?<parameter>[^:]+):\s*(?<value>[\w']+(?:\s*\([^)]*\))*)\s*(?<description>.*)" test_str = ("pts_time: PTS: 1741047514> Time: 19345 sec > (hh:mm:ss.ms) 05:22:24.972\n" "pts_time: PTS: 1741047514 [0x67C646DA] > Time: 19345 sec > (hh:mm:ss.ms) 05:22:24.972\n" "private_indicator: '0' reserved: '11'\n" "section_length: 0x39 (57) protocol_version: 0\n" "encrypted_packet: 0 no part of this message is encrypted\n" "encryption_algorithm: 0 No encryption\n" "pts_adjustment: 0xFFFF7F18 (33000) > Time: 95443.4 sec > (hh:mm:ss.ms) 26:30:43.351\n" "cw_index: 0x00 (0) tier: 0x0FFF (4095)\n" "splice_command_length: 0x0005 (5) splice_command_type: 0x06 (6) time_signal [] time_signal: > Time: 19345 sec > (hh:mm:ss.ms) 05:22:24.972\n" "time_specified_flag: 1 presence of the pts_time field\n" "reserved: 0x3F (63) descriptor_loop_length: 35 [] Descriptors: [] segmentation_descriptor (0x02): Content Identification (0x01)\n" "descriptor_tag: 0x02 (2) descriptor_length: 0x21 (33)\n" "identifier: 0x43554549 (CUEI) segmentation_event_id: 0x00000001 (1)\n" "segmentation_event_cancel_indicator: '0' a previously sent segmentation event, identified by segmentation_event_id, has NOT been cancelled\n" "reserved: 0x7F (127) program_segmentation_flag: '1' the message refers to a Program Segmentation Point and that the mode is the Program Segmentation Mode whereby all PIDs/components of the program are to be segmented\n" "segmentation_duration_flag: '0' No presence of segmentation_duration field\n" "delivery_not_restricted_flag: '1' the next five bits are reserved\n" "reserved: 0x1F (31) segmentation_upid_type: 0x01 (1) Deprecated: use type 0x0C; The segmentation_upid does not follow a standard naming scheme.\n" "segmentation_upid_length: 0x12 (18) segmentation_type_id: 0x01 (1) Content Identification\n" "segment_num: 0x01 (1) segments_expected: 0x01 (1)\n" "CRC_32: 0x46D15AF3 CRC OK\n\n" "// try this one first\n" "// (a) ^(?<parameter>[^:]+)\\:\\s*(?:(?<value>[A-Za-z]+\\:\\s*[^>]+))\n" "// (b) ^(?<parameter>[^:]+)\\:\\s*(?:(?<value>[A-Za-z]+\\:\\s*[^>]+))\\s*(?<description>.*)\n\n" "// in case of no match of the above one use the second\n" "// (a) ^(?<parameter>[^:]+):\\s*(?<value>[\\w']+(?:\\s*\\([^)]*\\))*)\n" "// (b) ^(?<parameter>[^:]+):\\s*(?<value>[\\w']+(?:\\s*\\([^)]*\\))*)\\s*(?<description>.*)\n\n" "// substitution:\n" "// [\"$1\", \"$2\", \"$3\"]\n") 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