Regular Expressions 101

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Function

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  • Substitution
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  • Unit Tests (25)
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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
Processing...

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 = "^(?:(?P<type>(?:feat)|(?:fix)|(?:docs)|(?:style)|(?:refactor)|(?:test)|(?:merge)|(?:chore))(?: \\((?P<issue>.+)\\))?: (?P<subject>[A-Z0-9].{0,48}(?!\\.).?)\\n?)(?:\\n(?P<body>(?:.*\\n?)+))*$"; final String string = "feat: Summarize changes in around 50 characters or less\n\n" + "More detailed explanatory text, if necessary. Wrap it to about 72\n" + "characters or so. In some contexts, the first line is treated as the\n" + "subject of the commit and the rest of the text as the body. The\n" + "blank line separating the summary from the body is critical (unless\n" + "you omit the body entirely); various tools like `log`, `shortlog`\n" + "and `rebase` can get confused if you run the two together.\n\n" + "Explain the problem that this commit is solving. Focus on why you\n" + "are making this change as opposed to how (the code explains that).\n" + "Are there side effects or other unintuitive consequences of this\n" + "change? Here's the place to explain them.\n\n" + "Further paragraphs come after blank lines.\n\n" + " - Bullet points are okay, too\n\n" + " - Typically a hyphen or asterisk is used for the bullet, preceded\n" + " by a single space, with blank lines in between, but conventions\n" + " vary here\n\n" + "If you use an issue tracker, put references to them at the bottom,\n" + "like this:\n\n" + "Resolves: #123\n" + "See also: #456, #789"; final Pattern pattern = Pattern.compile(regex, 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