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

/
/
gmi

Test String

Code Generator

Language

Generated Code

$re = '/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*))*/mi'; $str = '// in_out.cpp: определяет точку входа для консольного приложения. #include "stdafx.h" #include <iostream> using namespace std; int main() { int a, b; // объявление переменных типа int, то есть в таких переменных хранятся только целые числа cout << "Vvedite pervoe chislo: "; cin >> a; cout << "Vvedite vtoroe chislo: "; cin >> b; if (a > b) cout << a << " > " << b << endl; // печатать данное сообщение if (a < b and c ==k or (s == f && f==d)) { cout << a << " < " << b << endl; cout << a << " < " << b << endl; cout << a << " < " << b << endl; cout << a << " < " << b << endl; cout << a << " < " << b << endl; cout << a << " < " << b << endl; if (sdfsdf) { sdfsdf } cout << a << " < " << b << endl; cout << a << " < " << b << endl; cout << a << " < " << b << endl; } if (a == b) // если а = b cout << a << " = " << b << endl; // в теле условного оператора опущены фигурные скобочки system("pause"); return 0; } if (a <b) { cout << a << " < " << b << endl; } if (a <b cvxcv sdfsd sdfsd sdfds ) { cout << a << " < " << b << endl; } else { dsfsdfsdf } if (var1 == "("){ echo "{в"; } if(boolean_expression 1) { // Executes when the boolean expression 1 is true } else if(boolean_expression 2) { // Executes when the boolean expression 2 is true } else if( boolean_expression 3) { // Executes when the boolean expression 3 is true } else { // executes when the none of the above condition is true. } '; preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0); // Print the entire match result var_dump($matches);

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 PHP, please visit: http://php.net/manual/en/ref.pcre.php