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"Received\s*:\s*by.*?(?P<Hop_Time>[0-9]{2}:[0-9]{2}:[0-9]{2})" test_str = ("Received:by mail-ed1-f69.google.com with SMTP id b21so4825939edt.18 for <budsarin.temsawat@aaa.co.th>; Wed 26 Jun 2019 18:04:32 -0700 (PDT) X-Google-DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=q04dTGosad+dTkX0DLE3TZT1LvNQX45YXfBh9AMeFco=; b=a5lzAB+U25QwdRDIw/0H1CT0SGRZNRyiTRNJ1jg5kgfg4IPhyOeWkqm72Ay w1VV8x3kVzv2jgAyF9/W57NcN43CyejW+ag086fJy2LmqMM03q/Voz7A89av nxsiIx0V5BOWkcSl3XdBOqQD9imxNL9Bermp548jum51kOopBX6uALrW+Yy qfSravlh8ONQ8YTOC47iSPBQhCh0b1lMO51p5e6zeIwcLUO62YYl/N3DUKDeN vduYOj/HAEVQXqfO64Fepx6U2QAi2Lg6hM2zcdKMgDR/Wdj/QehmFj+Fl Ptag== X-Gm-Message-State:APjAAAUcvfjYPCkT4REkr2t4IE6NeIZTGRWloRcKwy0gyZHb MynBUQciUYH9gQifGU0TaLv4ddVqHoFhsAXIsniMfUuXeetryhOwO+1bS26ze2SA fvZIq6qEaOgJlMJZt9nUOMYE2WspxuBWVosL2kKutE99i5q9VzsMDuK+2wlVL4y MZOpqMIpA6mfKRnzX1cwrcvA9PPbiWI/x7Ldg0kx+kCRuuJQ== X-Received:by 2002:a17:906:3ed1:: with SMTP id d17mr602603ejj.285.1561597403255; Wed 26 Jun 2019 18:03:23 -0700 (PDT) X-Google-Smtp-Source:APXvYqw4u4lwcGK+asj4XNave7dmVhuneOG1zr46FOmbsgkj0gup9KvdYrzB1LJXS2zMNXf+I= X-Received:by 2002:a17:906:3ed1:: with SMTP id d17mr602584ejj.285.1561597403013; Wed 26 Jun 2019 18:03:23 -0700 (PDT) MIME-Version:1.0 References:<CAB-UEWaNHyJz4EyotLZA@mail.gmail.com> <CAB-UEWavdVz0J+ySP5u_GGZm+DVRg@mail.gmail.com> <CANAFqSiHpjuU5VNQ57MSwc9FuGfwMEu49EvSQ@mail.gmail.com> <CAB-UEWZBhEzT2QxwsBk-XBfzf7j0qHr5O7tyUxwQw@mail.gmail.com> <CANAFqSiKEMRGkFsA2awnVg5zKSmih6iGOAv7Ng@mail.gmail.com> In-Reply-To:<CANAFqSiKEMRGkFsA2=4wnVg5zKSmih6iGOAv7Ng@mail.gmail.com> From:Sirisri Jitvatkun <sirisri.jitvatkun@bbb.co.th> Date:Thu 27 Jun 2019 08:03:11 +0700\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