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

/
/
gimx

Test String

Code Generator

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "^ \n" + "# Uncomment to allow prefix continuation (second letter of a dangling match)\n" + "# ([abcdefghiklmnoprstuvy\\ ])?\n" + "( \\\n" + " |(?: # Single-letter elements\n" + " [BCFHIKNOPSUVWY]\n" + " )\n" + " |(?: # Two-letter elements.\n" + " (?:A[cglmrstu])|(?:B[aehikr])|(?:C[adeflmnorsu])|(?:D[bsy])\n" + " | (?:E[rsu])|(?:F[elmr])|(?:G[ade])|(?:H[efgos])|(?:I[nr])\n" + " | (?:K[r])|(?:L[airuv])|(?:M[cdgnot])|(?:N[abdehiop])\n" + " | (?:O[gs])|(?:P[abdmortu])|(?:R[abefghnu])|(?:S[bcegimnr])\n" + " | (?:T[abcehilms])|(?:X[e])|(?:Yb)|(?:Z[nr])\n" + " )\n" + " |(?: # Smushed trigrams. No need to go past trigrams because two twos make four\n" + " (?:A(?:ga|gd|ge|la|lr|md|mg|mt|ra|re|rg|ta|te|tl|tm))\n" + " |(?:E(?:ra|re|rg))\n" + " |(?:G(?:ag|al|am|ar|at|er))\n" + " |(?:L(?:ag|al|am|ar|at|ra|re|rg))\n" + " |(?:M(?:ga|gd|ge|ta|te|tl|tm))\n" + " |(?:R(?:ag|al|am|ar|at|er|ga|gd|ge))\n" + " |(?:T(?:ag|al|am|ar|at|er|la|lr|md|mg|mt))\n" + " |(?:X(?:er))\n" + " |(?:Z(?:ra|re|rg))\n" + " )\n" + "# repeated any number of times\n" + ")+\n" + "# Uncomment to allow last letter if it's a potential first letter of the next word\n" + "# ([ADEGLMRTXZ]\\ *)?\n" + "$"; final String string = "**(See bottom for Javascript/one-line version)**\n" + "If you want continuation -- to look for \"fez\" \"rave\" \"rites\" chains, strike the second and second-to-last lines. Latex needs a suffix and ear needs a prefix.\n" + "latex\n" + "ear\n" + "latexear\n" + "fez\n" + "rave\n" + "rites\n" + "fezraverites\n" + "if you don't want overlap, comment out the big group with (?<=..) tests. Walter and lag will not match: lag is La + Ag but can't be L+Ag or La+G; walter is W+Al+Te+Er but there's no single A, L, T, E or R to make it a strict chain of elements.\n" + "Walter\n" + "aga\n" + "McLvinandfezrobHogwartsWizrdsofMoney\n" + "## Match:\n" + "McLvIn\n" + "McLvinandfezrobHogwartsWizrdsofMoney\n" + "zr\n" + "McLvinand\n" + "ergo\n" + "Orgasmicallabkitscashflow\n" + "update\n" + "Organicfurbies\n" + "Babkes\n" + "WalterWhite\n" + "That\n" + "ibexesnogladybirds\n" + "Xenophobic\n" + "picnicforgus\n" + "snapes\n" + "siriusblack\n\n\n" + "## match until last letter, and last letter potentially starts a new word (allows continuation)\n" + "fez\n" + "McLvinandfez\n" + "bobatea\n\n" + "# La + At + Te\n" + "late\n" + "# the x awaits an e in the next word\n" + "latex\n" + "# N + Nd + Dy + Y + Yb\n" + "ndyb\n" + "# the a is a potential continuation\n" + "andy\n" + "# ...but the x can't be a second letter\n" + "xndyb\n\n" + "## Don't Match at some interior point in line\n" + "Jemmamead\n" + "## Don't Match anywhere in line\n" + "JemmaQmead\n\n" + "### For Javascript:\n\n" + "^([abcdefghiklmnoprstuvy\\s])?(\\ |(?:[BCFHIKNOPSUVWY])|(?:(?:A[cglmrstu])|(?:B[aehikr])|(?:C[adeflmnorsu])|(?:D[bsy])|(?:E[rsu])|(?:F[elmr])|(?:G[ade])|(?:H[efgos])|(?:I[nr])|(?:K[r])|(?:L[airuv])|(?:M[cdgnot])|(?:N[abdehiop])|(?:O[gs])|(?:P[abdmortu])|(?:R[abefghnu])|(?:S[bcegimnr])|(?:T[abcehilms])|(?:X[e])|(?:Yb)|(?:Z[nr]))|(?:(?:A(?:ga|gd|ge|la|lr|md|mg|mt|ra|re|rg|ta|te|tl|tm))|(?:E(?:ra|re|rg))|(?:G(?:ag|al|am|ar|at|er))|(?:L(?:ag|al|am|ar|at|ra|re|rg))|(?:M(?:ga|gd|ge|ta|te|tl|tm))|(?:R(?:ag|al|am|ar|at|er|ga|gd|ge))|(?:T(?:ag|al|am|ar|at|er|la|lr|md|mg|mt))|(?:X(?:er))|(?:Z(?:ra|re|rg))))+([ADEGLMRTXZ]\\ *)?$"; final Pattern pattern = Pattern.compile(regex, Pattern.CASE_INSENSITIVE | Pattern.MULTILINE | 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