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

r"
"
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"gateway=((\d{1,3}(\.\d{1,3}){3},)*172.17.2.1(,\d{1,3}(\.\d{1,3}){3})*) " test_str = (" 0 A S dst-address=0.0.0.0/0 gateway=172.29.150.17,172.29.150.25 gateway-status=172.29.150.17 reachable via gre-tunnel1,172.29.150.25 reachable via gre-tunnel2 distance=10 scope=30 target-scope=10 routing-mark=INET-SERVERS \n" " 1 A S dst-address=0.0.0.0/0 gateway=172.17.2.1 gateway-status=172.17.2.1 reachable via bridge-outside1 distance=1 scope=30 target-scope=10 routing-mark=to-outside1 \n" " 2 A S dst-address=0.0.0.0/0 gateway=172.17.3.1 gateway-status=172.17.3.1 reachable via bridge-outside2 distance=1 scope=30 target-scope=10 routing-mark=to-outside2 \n" " 3 A S dst-address=0.0.0.0/0 gateway=172.17.2.1,172.17.3.129 gateway-status=172.17.2.1 reachable via bridge-outside1,172.17.3.129 unreachable distance=1 scope=30 target-scope=10 \n" " 4 A S dst-address=10.0.0.0/8 pref-src=10.150.25.253 gateway=172.29.150.17,172.29.150.25 gateway-status=172.29.150.17 reachable via gre-tunnel1,172.29.150.25 reachable via gre-tunnel2 distance=10 scope=30 target-scope=10 \n" " 5 ADC dst-address=10.150.25.0/24 pref-src=10.150.25.253 gateway=bridge-mgmt-inside gateway-status=bridge-mgmt-inside reachable distance=0 scope=10 \n" " 6 ADC dst-address=10.150.26.0/24 pref-src=10.150.26.253 gateway=bridge-wireless-tensor-dev gateway-status=bridge-wireless-tensor-dev reachable distance=0 scope=10 \n" " 7 ADC dst-address=10.150.27.0/24 pref-src=10.150.27.253 gateway=bridge-public gateway-status=bridge-public reachable distance=0 scope=10 \n" " 8 ADC dst-address=10.150.28.0/23 pref-src=10.150.28.253 gateway=bridge-inside2 gateway-status=bridge-inside2 reachable distance=0 scope=10 \n" " 9 ADC dst-address=172.17.2.0/25 pref-src=172.17.2.12 gateway=bridge-outside1 gateway-status=bridge-outside1 reachable distance=0 scope=10 \n" "10 ADC dst-address=172.17.3.0/25 pref-src=172.17.3.12 gateway=bridge-outside2 gateway-status=bridge-outside2 reachable distance=0 scope=10 \n" "11 ADC dst-address=172.29.150.16/29 pref-src=172.29.150.22 gateway=gre-tunnel1 gateway-status=gre-tunnel1 reachable distance=0 scope=10 \n" "12 ADC dst-address=172.29.150.24/29 pref-src=172.29.150.30 gateway=gre-tunnel2 gateway-status=gre-tunnel2 reachable distance=0 scope=10 ") 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