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
  • Match everything enclosed
    (?:...)
  • Capture everything enclosed
    (...)
  • 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"ip dhcp excluded-address ([\d\.]*)($| ([\d\.]*)$)" test_str = ("ip dhcp excluded-address 10.10.8.1 10.10.8.100\n" "ip dhcp excluded-address 10.8.8.1 10.8.9.0\n" "ip dhcp excluded-address 192.168.0.1 192.168.0.10\n" "ip dhcp excluded-address 10.10.9.12\n" "ip dhcp excluded-address 10.10.9.14\n" "!\n" "ip dhcp pool Pool1\n" " network 10.10.8.0 255.255.248.0\n" " update dns both override\n" " dns-server 10.10.1.10 10.10.1.11 \n" " default-router 10.10.8.1 \n" " lease 8\n" "!\n" "ip dhcp pool Pool2\n" " network 10.8.8.0 255.255.248.0\n" " update dns both override\n" " default-router 10.8.8.1 \n" " dns-server 10.10.1.10 10.10.1.11 \n" " lease 8\n" "!\n" "ip dhcp pool Pool3\n" " network 192.168.0.0 255.255.255.0\n" " update dns both override\n" " dns-server 10.10.1.10 10.10.1.11 \n" " default-router 192.168.0.1 \n" " lease 8\n" "!\n" "ip dhcp pool Device1\n" " host 10.10.10.84 255.255.248.0\n" " client-identifier 0100.24ee.065d.3e\n" "!\n" "ip dhcp pool Device2\n" " host 10.10.10.115 255.255.248.0\n" " client-identifier 0194.c691.6a43.3f\n" "!\n" "ip dhcp pool Device3\n" " host 10.10.10.250 255.255.248.0\n" " client-identifier 0194.c691.fb53.7e\n" "!\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