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

~
~
xsmg

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* # white spaces\n" + "########################## KEYS START ##########################\n" + "(?: # We\\'ll use this to make keys optional\n" + "(?P<keys> # named group: keys\n" + "\\d+ # match digits\n" + "| # or\n" + "\"(?(?=\\\\\\\\\")..|[^\"])*\" # match string between \"\", works even 4 escaped ones \"hello \\\" world\"\n" + "| # or\n" + "\\'(?(?=\\\\\\\\\\')..|[^\\'])*\\' # match string between \\'\\', same as above :p\n" + "| # or\n" + "\\$\\w+(?:\\[(?:[^[\\]]|(?R))*\\])* # match variables $_POST, $var, $var[\"foo\"], $var[\"foo\"][\"bar\"], $foo[$bar[\"fail\"]]\n" + ") # close group: keys\n" + "########################## KEYS END ##########################\n" + "\\s* # white spaces\n" + "=> # match =>\n" + ")? # make keys optional\n" + "\\s* # white spaces\n" + "########################## VALUES START ##########################\n" + "(?P<values> # named group: values\n" + "\\d+ # match digits\n" + "| # or\n" + "\"(?(?=\\\\\\\\\")..|[^\"])*\" # match string between \"\", works even 4 escaped ones \"hello \\\" world\"\n" + "| # or\n" + "\\'(?(?=\\\\\\\\\\')..|[^\\'])*\\' # match string between \\'\\', same as above :p\n" + "| # or\n" + "\\$\\w+(?:\\[(?:[^[\\]]|(?R))*\\])* # match variables $_POST, $var, $var[\"foo\"], $var[\"foo\"][\"bar\"], $foo[$bar[\"fail\"]]\n" + "| # or\n" + "array\\s*\\((?:[^()]|(?R))*\\) # match an array()\n" + "| # or\n" + "\\[(?:[^[\\]]|(?R))*\\] # match an array, new PHP array syntax: [1, 3, 5] is the same as array(1,3,5)\n" + "| # or\n" + "(?:function\\s+)?\\w+\\s* # match functions: helloWorld, function name\n" + "(?:\\((?:[^()]|(?R))*\\)) # match function parameters (wut), (), (array(1,2,4))\n" + "(?:(?:\\s*use\\s*\\((?:[^()]|(?R))*\\)\\s*)? # match use(&$var), use($foo, $bar) (optionally)\n" + "\\{(?:[^\\{\\}]|(?R))*\\} # match \\{ whatever\\}\n" + ")?;? # match ; (optionally)\n" + ") # close group: values\n" + "########################## VALUES END ##########################\n" + "\\s* # white spaces"; final String string = "0 => \"a\", 123 => 123, 1234, 'got problem ?', \n" + " \"a\" => $GlobalScopeVar, \n" + "$test_further => function test($noway){echo \"this works too !!!\";}, \n" + "\"yellow\" => \"blue\",\n" + " \"b\" => array(\"nested\"=>array(1,2,3), \"nested\"=>array(1,2,3),\"nested\"=>array(1,2,3)), \n" + "\"c\" => function() use (&$VAR) { return isset($VAR) ? \"defined\" : \"undefined\" ; },\n" + " \"bug\",$var = $_POST[\"test];\n" + " \"fixed\", \n" + "\"mwahahahaa\" => \"Yeaaaah\",\n" + "$_POST[\"hello\"][\\'world\\'] => array(\"is\", \"actually\", \"An array !\")"; final Pattern pattern = Pattern.compile(regex, Pattern.COMMENTS | Pattern.DOTALL | 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