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"
"
gim

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 = "^\\w+(?=\\s+OBJECT-TYPE)"; final String string = "STEELHEAD-MIB DEFINITIONS ::= BEGIN\n\n" + "IMPORTS\n" + " OBJECT-TYPE, MODULE-IDENTITY, NOTIFICATION-TYPE, Unsigned32,\n" + " TimeTicks, IpAddress, Counter32, Counter64 FROM SNMPv2-SMI\n" + " DateAndTime FROM SNMPv2-TC\n" + " products FROM RBT-MIB;\n\n" + "steelhead MODULE-IDENTITY\n" + " LAST-UPDATED \"201401070000Z\"\n" + " ORGANIZATION \"Riverbed Technology, Inc.\"\n" + " CONTACT-INFO\n" + " \" Riverbed Technical Support\n" + " support@riverbed.com\"\n" + " DESCRIPTION \"Steelhead MIB\"\n" + " REVISION \"201401070000Z\"\n" + " DESCRIPTION \"Connection forwarding cluster incompatible trap\"\n" + " REVISION \"201301250000Z\"\n" + " DESCRIPTION \"Corrections in descriptions of some traps\"\n" + " REVISION \"201210170000Z\"\n" + " DESCRIPTION \"Added trap for CF Peer IPv6 incompatible alarm\"\n" + " REVISION \"201202030000Z\"\n" + " DESCRIPTION \"Updated for 7.0.1\"\n" + " ::= { products 1 }\n\n" + "system OBJECT IDENTIFIER\n" + " ::= { steelhead 1 }\n\n" + "status OBJECT IDENTIFIER\n" + " ::= { steelhead 2 }\n\n" + "config OBJECT IDENTIFIER\n" + " ::= { steelhead 3 }\n\n" + "alarms OBJECT IDENTIFIER\n" + " ::= { steelhead 4 }\n\n" + "statistics OBJECT IDENTIFIER\n" + " ::= { steelhead 5 }\n\n" + "--\n" + "--\n" + "-- SYSTEM\n" + "--\n" + "--\n\n" + "model OBJECT-TYPE\n" + " SYNTAX OCTET STRING\n" + " MAX-ACCESS read-only\n" + " STATUS current\n" + " DESCRIPTION\n" + " \"Appliance model\"\n" + " ::= { system 1 }\n\n" + "serialNumber OBJECT-TYPE\n" + " SYNTAX OCTET STRING\n" + " MAX-ACCESS read-only\n" + " STATUS current\n" + " DESCRIPTION\n" + " \"Appliance serial number\"\n" + " ::= { system 2 }\n\n" + "systemVersion OBJECT-TYPE\n" + " SYNTAX OCTET STRING\n" + " MAX-ACCESS read-only\n" + " STATUS current\n" + " DESCRIPTION\n" + " \"System software version string\"\n" + " ::= { system 3 }\n\n\n\n" + "--\n" + "--\n" + "-- STATUS\n" + "--\n" + "--\n\n" + "systemClock OBJECT-TYPE\n" + " SYNTAX DateAndTime\n" + " MAX-ACCESS read-only\n" + " STATUS current\n" + " DESCRIPTION\n" + " \"System clock time\"\n" + " ::= { status 1 }\n\n" + "health OBJECT-TYPE\n" + " SYNTAX OCTET STRING\n" + " MAX-ACCESS read-only\n" + " STATUS current\n" + " DESCRIPTION\n" + " \"Current health of the system. The value is one amongst\n" + " Healthy, Admission Control, Degraded, Critical\"\n" + " ::= { status 2 }\n\n" + "serviceStatus OBJECT-TYPE\n" + " SYNTAX OCTET STRING\n" + " MAX-ACCESS read-only\n" + " STATUS current\n" + " DESCRIPTION\n" + " \"Current status of the optimization service\"\n" + " ::= { status 3 }"; final Pattern pattern = Pattern.compile(regex, Pattern.CASE_INSENSITIVE | 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