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"
"
ms

Test String

Code Generator

Language

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "(lease\\s(?P<ip>[0-9\\.]+)\\s\\{.+\\})"; final String string = "lease 10.31.31.131 {\n" + " starts 0 2014/08/31 14:54:11;\n" + " ends 0 2014/08/31 15:04:11;\n" + " cltt 0 2014/08/31 14:54:11;\n" + " binding state active;\n" + " next binding state free;\n" + " rewind binding state free;\n" + " hardware ethernet d0:e7:82:19:8e:ec;\n" + " set ddns-rev-name = \"131.31.31.10.in-addr.arpa.\";\n" + " set ddns-txt = \"0044522956d8e56b0f40798743a0660994\";\n" + " set ddns-fwd-name = \"Chromecast.example.\";\n" + " client-hostname \"Chromecast\";\n" + "}\n" + "lease 10.31.31.133 {\n" + " starts 0 2014/08/31 14:54:51;\n" + " ends 0 2014/08/31 15:04:51;\n" + " cltt 0 2014/08/31 14:54:51;\n" + " binding state active;\n" + " next binding state free;\n" + " rewind binding state free;\n" + " hardware ethernet 00:18:0a:22:2f:9f;\n" + " uid \"\\001\\000\\030\\012\\\"/\\237\";\n" + " set ddns-rev-name = \"133.31.31.10.in-addr.arpa.\";\n" + " set ddns-txt = \"31897a4f3a66a2733b86a7cd3b0b0b2923\";\n" + " set ddns-fwd-name = \"ap-1-00180a222f9f.example.\";\n" + " client-hostname \"ap-1-00180a222f9f\";\n" + "}\n"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE | Pattern.DOTALL); final Matcher matcher = pattern.matcher(string); if (matcher.find()) { System.out.println("Full match: " + matcher.group(0)); for (int i = 1; i <= matcher.groupCount(); i++) { System.out.println("Group " + i + ": " + matcher.group(i)); } } } }

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 Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html