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

/
/
gmi

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 = "if\\s*\\((?P<conditional>(?:(?:(?:\"(?:(?:\\\\\")|[^\"])*\")|(?:'(?:(?:\\\\')|[^'])*'))|[^\\(\\)]|\\((?1)\\))*+)\\)\\s*(?P<true_body>(?:\\{(?:(?:(?:\"(?:(?:\\\\\")|[^\"])*\")|(?:'(?:(?:\\\\')|[^'])*'))|[^\\{\\}]|\\{(?2)\\})*+\\})|(?:[^\\{\\}\\n]*))\\s*(?:(?:else\\s+?(?!if)(?P<else_body>(?:\\{(?:(?:(?:(?:\"(?:(?:\\\\\")|[^\"])*\")|(?:'(?:(?:\\\\')|[^'])*'))|[^\\{\\}]|\\{(?3)\\})+)\\})|(?:[^\\{\\}\\n])*)\\s*)|(?:else\\s*if\\s*\\((?P<else_if_condition>(?:(?:(?:\"(?:(?:\\\\\")|[^\"])*\")|(?:'(?:(?:\\\\')|[^'])*'))|[^\\(\\)]|\\((?4)\\))+)\\)\\s*(?P<else_if_body>(?:(?:\\{(?:(?:(?:\"(?:(?:\\\\\")|[^\"])*\")|(?:'(?:(?:\\\\')|[^'])*'))|[^\\{\\}]|\\{(?5)\\})+\\})|(?:[^\\{\\}\\n]*)))\\s*))*"; final String string = "// in_out.cpp: определяет точку входа для консольного приложения.\n" + " \n" + "#include \"stdafx.h\"\n" + "#include <iostream>\n" + "using namespace std;\n" + " \n" + "int main()\n" + "{\n" + " int a, \n\n\n" + "b; // объявление переменных типа int, то есть в таких переменных хранятся только целые числа\n" + " cout << \"Vvedite \n\n" + "pervoe \n\n" + "chislo: \";\n" + " cin >> a;\n" + " cout << \"Vvedite vtoroe chislo: \";\n" + " cin >> b;\n" + " if (a > b) \n" + " cout << a << \" > \" << b << endl; // печатать данное сообщение\n" + " \n" + " if (a <\n" + "b and c ==k\n" + " or (s == f && f==d))\n" + " {\n" + " cout << a << \" < \" << b << endl;\n" + " cout << a << \" < \" << b << endl;\n" + " cout << a << \" < \" << b << endl;\n" + " cout << a << \" < \" << b << endl;\n" + " cout << a << \" < \" << b << endl;\n" + " cout << a << \" < \" << b << endl;\n" + " if (sdfsdf) {\n" + "sdfsdf\n" + " }\n\n" + " cout << a << \" < \" << b << endl;\n" + " cout << a << \" < \" << b << endl;\n\n" + " cout << a << \" < \" << b << endl;\n" + " }\n" + " if (a == b) // если а = b\n" + " cout << a << \" = \" << b << endl; // в теле условного оператора опущены фигурные скобочки\n" + " system(\"pause\");\n" + " return 0;\n" + "}\n\n\n" + " if (a <b) {\n" + " cout << a << \" < \" << b << endl;\n" + " }\n\n\n" + " if (a <b\n" + "cvxcv sdfsd sdfsd \n" + "sdfds \n\n" + ") {\n" + " cout << a << \" < \" << b << endl;\n" + " } else {\n" + "dsfsdfsdf\n" + "}\n\n" + "if (var1 == \"(\"){\n" + " echo \"{в\";\n" + "}\n\n\n" + "if(boolean_expression 1)\n" + "{\n" + " // Executes when the boolean expression 1 is true\n" + "}\n" + "else if(boolean_expression 2)\n" + "{\n" + " // Executes when the boolean expression 2 is true\n" + "}\n" + "else if( boolean_expression 3)\n" + "{\n" + " // Executes when the boolean expression 3 is true\n" + "}\n" + "else \n" + "{\n" + " // executes when the none of the above condition is true.\n" + "}\n\n"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE | Pattern.CASE_INSENSITIVE); 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