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

/
/

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 = "(?:^(?:[A-Za-z0-9+\\/]{4}\\n?)*(?:[A-Za-z0-9+\\/]{2}==|[A-Za-z0-9+\\/]{3}=)$)"; final String string = "hQGkA8uYb/u24XuEAQzAh5dH2QUPv5rQ+uHwVQQShCgmgJzlOAq+L6Ld4l4P0MOeUYK7Zvt7HiYM\n" + "MzH5Pdi+VfiW0JWDqTdvQZS6o0SfBzoZqwqplAofLH+7hlu8qS0n6FFxXk2b4N5InMf/zWlqpDb6\n" + "oeGZQBbLJy69drKzpJYvqMM+OuzLUA4Wwv/WfwGtHo/fQ3H2JSFwPJz3QHuqvTrnIhO23fZa8Qpd\n" + "M36LBbX3yqrmrJo63NHy9QL9eF6+/WU7qsKOxGSm2QlDaREKx6ZlXgZ+FY7SEt1C6PHPXhggf4Ts\n" + "EF5rb+0goEniDbgiofYpUt0+aLkwsNnMYHx0+yAelPP45ZbCKxQe1Tk3gq5oAspWvUAvt6SqmNW5\n" + "CrakBXYSIpNqHWdjdW75yeUYPKIi1X1SZi1mVGy0ayrOGoPbOY6C77JwGMxqEOZtDLBiy/u9g1II\n" + "Zy1dm3UxhX/Tir2Cg+5kTAVQ6qqliklhGSCcYw0rNMfl+q151zKu4/j9id5pHnrkjnjrV1odz3u/\n" + "aBKxLpzf8cf2BlYdRooqvFIbdJULftmn0lABukKc0eaPclSdz//DzTU318fpHnFbzlUpi82UVNL4\n" + "IUqUviQNw7SX41v90N39iNP3JmczkN8J70+o7NLYlcvp4xXIFOcRaDrinbCcXT1WfQ=="; final Pattern pattern = Pattern.compile(regex); final Matcher matcher = pattern.matcher(string); if (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