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

/
/
g

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 = "\\b(?<!\\d.)(3[47]\\d{2}([ -]?)(?!(\\d)\\3{5}|123456|234567|345678|424242|545454)\\d{6}\\2(?!(\\d)\\4{4})\\d{5}|((4\\d|5[1-5]|65)\\d{2}|6011)([ -]?)(?!(\\d)\\8{3}|4242|5454|1234|3456|5678|2345|4567)\\d{4}\\7(?!(\\d)\\9{3})\\d{4}\\7\\d{4})(\\b|\\s)(?!.\\d\\d)"; final String string = "ALL strings in the first section should match\n" + "some 4270446050075048\n" + "4270-4460-5007-5048\n" + "this:4270 4460 5007 5048.\n" + "4270 4460 5007 5048 4/20\n" + "4270 4460 5007 5048 what\n" + "4270 4460 5007 5048\n" + "4270 4460 5007 5048 12/20 \n" + "5105105105105100\n" + "5200828282828210\n\n" + "--- (the following should not match - test numbers)\n" + "5454545454545454\n" + "4123456789012345\n" + "4242424242424242\n" + "42704460500750a8\n" + "4111111111111111\n" + "5111111111111111\n" + "5555555555555555\n" + "3333333333333333\n" + "3111111111111111\n\n" + "--- (the following should NOT match)\n" + "4270 4460 5007 5048 1234\n" + "4270\n" + "4270 4460 5007 504\n" + "42811293test123\n" + "427044605007504812345083 5095 5179 5157 5219 5187 5095 <--- FALSE POSITIVE (contains valid CC but has lots of exra digits)\n" + "this:4270 4460 5007 50482\n" + "4270 4460 5007 5048 123\n" + "4270 4460 5007 5048 1234\n\n" + "Known False positive (test number):\n" + "5535 3545 5455 4444\n"; final Pattern pattern = Pattern.compile(regex); 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