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 = "(?:FN:Tom )((.|\\n)*)(?:\\nEND:VCARD)"; final String string = "FN:Tom root:x:0:0:root:/root:/bin/bash\n" + "daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin\n" + "bin:x:2:2:bin:/bin:/usr/sbin/nologin\n" + "sys:x:3:3:sys:/dev:/usr/sbin/nologin\n" + "sync:x:4:65534:sync:/bin:/bin/sync\n" + "games:x:5:60:games:/usr/games:/usr/sbin/nologin\n" + "man:x:6:12:man:/var/cache/man:/usr/sbin/nologin\n" + "lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin\n" + "mail:x:8:8:mail:/var/mail:/usr/sbin/nologin\n" + "news:x:9:9:news:/var/spool/news:/usr/sbin/nologin\n" + "uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin\n" + "proxy:x:13:13:proxy:/bin:/usr/sbin/nologin\n" + "www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin\n" + "backup:x:34:34:backup:/var/backups:/usr/sbin/nologin\n" + "list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin\n" + "irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin\n" + "gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin\n" + "nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin\n" + "systemd-timesync:x:100:102:systemd Time Synchronization,,,:/run/systemd:/bin/false\n" + "systemd-network:x:101:103:systemd Network Management,,,:/run/systemd/netif:/bin/false\n" + "systemd-resolve:x:102:104:systemd Resolver,,,:/run/systemd/resolve:/bin/false\n" + "systemd-bus-proxy:x:103:105:systemd Bus Proxy,,,:/run/systemd:/bin/false\n" + "syslog:x:104:108::/home/syslog:/bin/false\n" + "_apt:x:105:65534::/nonexistent:/bin/false\n" + "messagebus:x:106:110::/var/run/dbus:/bin/false\n" + "uuidd:x:107:111::/run/uuidd:/bin/false\n" + "student:x:1000:1000:student,,,:/home/student:/bin/bash\n" + "sshd:x:108:65534::/var/run/sshd:/usr/sbin/nologin\n\n" + "END:VCARD"; 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