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

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "^\\s*((((([0-9A-Fa-f]{1,4})|\\*):){7}((([0-9A-Fa-f]{1,4})|\\*)|:))|(((([0-9A-Fa-f]{1,4})|\\*):){6}(:(([0-9A-Fa-f]{1,4})|\\*)|((25[0-5]|2[0-4]\\d|1\\d\\d|[1-9]?\\d)(\\.(25[0-5]|2[0-4]\\d|1\\d\\d|[1-9]?\\d)){3})|:))|(((([0-9A-Fa-f]{1,4})|\\*):){5}(((:(([0-9A-Fa-f]{1,4})|\\*)){1,2})|:((25[0-5]|2[0-4]\\d|1\\d\\d|[1-9]?\\d)(\\.(25[0-5]|2[0-4]\\d|1\\d\\d|[1-9]?\\d)){3})|:))|(((([0-9A-Fa-f]{1,4})|\\*):){4}(((:(([0-9A-Fa-f]{1,4})|\\*)){1,3})|((:(([0-9A-Fa-f]{1,4})|\\*))?:((25[0-5]|2[0-4]\\d|1\\d\\d|[1-9]?\\d)(\\.(25[0-5]|2[0-4]\\d|1\\d\\d|[1-9]?\\d)){3}))|:))|(((([0-9A-Fa-f]{1,4})|\\*):){3}(((:(([0-9A-Fa-f]{1,4})|\\*)){1,4})|((:(([0-9A-Fa-f]{1,4})|\\*)){0,2}:((25[0-5]|2[0-4]\\d|1\\d\\d|[1-9]?\\d)(\\.(25[0-5]|2[0-4]\\d|1\\d\\d|[1-9]?\\d)){3}))|:))|(((([0-9A-Fa-f]{1,4})|\\*):){2}(((:(([0-9A-Fa-f]{1,4})|\\*)){1,5})|((:(([0-9A-Fa-f]{1,4})|\\*)){0,3}:((25[0-5]|2[0-4]\\d|1\\d\\d|[1-9]?\\d)(\\.(25[0-5]|2[0-4]\\d|1\\d\\d|[1-9]?\\d)){3}))|:))|(((([0-9A-Fa-f]{1,4})|\\*):){1}(((:(([0-9A-Fa-f]{1,4})|\\*)){1,6})|((:(([0-9A-Fa-f]{1,4})|\\*)){0,4}:((25[0-5]|2[0-4]\\d|1\\d\\d|[1-9]?\\d)(\\.(25[0-5]|2[0-4]\\d|1\\d\\d|[1-9]?\\d)){3}))|:))|(:(((:(([0-9A-Fa-f]{1,4})|\\*)){1,7})|((:(([0-9A-Fa-f]{1,4})|\\*)){0,5}:((25[0-5]|2[0-4]\\d|1\\d\\d|[1-9]?\\d)(\\.(25[0-5]|2[0-4]\\d|1\\d\\d|[1-9]?\\d)){3}))|:)))\\s*$"; final String string = "2404:6800:4003:c02::8a\n" + "2404:6800:4003:804::200e\n" + "2001:4998:c:a06::2:4008\n" + "fe80::21d8:f50:c295:c4be\n" + "2001:cdba::e:9652\n" + "2001:cdba:0:0:0:0:3257:9652\n" + "2001:cdba::3257:9652\n" + "2001:cdba::1222\n" + "21DA:D3:0:2F3B:2AA:FF:FE28:9C5A\n" + "2001:cdba::1:2:3:3257:9652\n" + "2404::4003:804::200e\n" + "1234:Fd2:2:1:89::4500\n" + "1234:Fd2:12:1:89::4500\n" + "2001:DB8:0:0:0:0:0:*\n" + "2001:DB8:0:0:0:*:*:*\n" + "2001:DB8::0:*\n" + "2001:DB8:0:0:0:*:0:1\n" + "::\n" + "2001:DB8:0:0:0:*\n" + "2001:*:1\n" + "*\n"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE); final Matcher matcher = pattern.matcher(string); while (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