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

/
/
sxXg

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 = "#IPv4\n" + "(?<IPv4>\n" + " (?!0+\\.)\n" + " (?<byte>2(?:[0-4]\\d|5[0-5])|1?\\d{1,2})\n" + " (?:\\.(?&byte)){3}\n" + ")\n\n" + "#IPv6 from http://vernon.mauery.com/content/projects/linux/ipv6_regex\n" + "| (?<smb>[0-9a-f]{1,4}:){1,1} (?<sme>:[0-9a-f]{1,4}){1,6}\n" + "| (?&smb){1,2} (?&sme){1,5}\n" + "| (?&smb){1,3} (?&sme){1,4}\n" + "| (?&smb){1,4} (?&sme){1,3}\n" + "| (?&smb){1,5} (?&sme){1,2}\n" + "| (?&smb){1,6} (?&sme){1,1}\n" + "| ((?&smb){1,7}|:):\n" + "| :(?&sme){1,7}\n" + "| (?&smb){6} (?&IPv4)\n" + "| (?&smb){5} :?+ [0-9a-f]{1,4} :(?&IPv4)\n" + "| (?&smb){1,1} (?&sme){1,4} :(?&IPv4)\n" + "| (?&smb){1,2} (?&sme){1,3} :(?&IPv4)\n" + "| (?&smb){1,3} (?&sme){1,2} :(?&IPv4)\n" + "| (?&smb){1,4} (?&sme){1,1} :(?&IPv4)\n" + "| ((?&smb){1,5}|:) :(?&IPv4)\n" + "| :(?&sme){1,5} :(?&IPv4)\n"; final String string = "Valid\n" + "192.168.1.1\n" + "192.168.255.255\n\n" + "Invalid\n" + "0.0.0.0\n" + "0.0.0.1\n" + "0.0.0.255\n" + "1.0.0.255\n\n"; final Pattern pattern = Pattern.compile(regex, Pattern.DOTALL | Pattern.COMMENTS); 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