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

/
/
gms

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 = "^\\s*(enum[^\\{]*)\\s*(\\{)\\s*([^\\}]+)\\s*(\\};)"; final String string = "#include <iostream>\n" + " \n" + "// enum that takes 16 bits\n" + "enum smallenum: int16_t\n" + "{\n" + " a,\n" + " b,\n" + " c\n" + "};\n" + " \n" + " \n" + "// color may be red (value 0), yellow (value 1), green (value 20), or blue (value 21)\n" + "enum color\n" + "{\n" + " red,\n" + " yellow,\n" + " green = 20,\n" + " blue\n" + "};\n" + " \n" + "// altitude may be altitude::high or altitude::low\n" + "enum class altitude: char\n" + "{ \n" + " high='h',\n" + " low='l', // C++11 allows the extra comma\n" + "}; \n" + " \n" + "// the constant d is 0, the constant e is 1, the constant f is 3\n" + "enum\n" + "{\n" + " d,\n" + " e,\n" + " f = e + 2\n" + "};\n" + " \n" + "//enumeration types (both scoped and unscoped) can have overloaded operators\n" + "std::ostream& operator<<(std::ostream& os, color c)\n" + "{\n" + " switch(c)\n" + " {\n" + " case red : os << \"red\"; break;\n" + " case yellow: os << \"yellow\"; break;\n" + " case green : os << \"green\"; break;\n" + " case blue : os << \"blue\"; break;\n" + " default : os.setstate(std::ios_base::failbit);\n" + " }\n" + " return os;\n" + "}\n" + " \n" + "std::ostream& operator<<(std::ostream& os, altitude al)\n" + "{\n" + " return os << static_cast<char>(al);\n" + "}\n" + " \n" + "int main()\n" + "{\n" + " color col = red;\n" + " altitude a;\n" + " a = altitude::low;\n" + " \n" + " std::cout << \"col = \" << col << '\\n'\n" + " << \"a = \" << a << '\\n'\n" + " << \"f = \" << f << '\\n';\n" + "}"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE | Pattern.DOTALL); 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