Regular Expressions 101

Save & Share

Flavor

  • PCRE2 (PHP >=7.3)
  • PCRE (PHP <7.3)
  • ECMAScript (JavaScript)
  • Python
  • Golang
  • Java 8
  • .NET 7.0 (C#)
  • Rust
  • Regex Flavor Guide

Function

  • Match
  • Substitution
  • List
  • Unit Tests

Tools

Sponsors
There are currently no sponsors. Become a sponsor today!
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

/
/
gm

Test String

Code Generator

Generated Code

$re = '/matei 170 associative arrays/m'; $str = '<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Community Login</title> </head> <body> <h2>Community Login</h2> <form method="post"> <label for="username">Username:</label> <input type="text" name="username" id="username"><br><br> <label for="password">Password:</label> <input type="password" name="password" id="password"><br><br> <button type="submit" name="login">Login</button> </form> <?php $communityUsers = [ "GAM" => password_hash("gamgamstyle", PASSWORD_ARGON2ID), "MAO" => password_hash("gentoo", PASSWORD_ARGON2ID), "MaxiObe" => password_hash("iloveallmias", PASSWORD_ARGON2ID) ]; if (isset($_POST[\'login\'])) { $enteredUsername = $_POST[\'username\']; $enteredPassword = $_POST[\'password\']; if (!empty($enteredUsername) && !empty($enteredPassword)) { if (array_key_exists($enteredUsername, $communityUsers)) { if (password_verify($enteredPassword, $communityUsers[$enteredUsername])) { echo "<p style=\'color:green;\'>Login successful! Welcome, " . htmlspecialchars($enteredUsername) . " </p>"; } else { echo "<p style=\'color:red;\'>Incorrect password.</p>"; } } else { echo "<p style=\'color:red;\'>Username not found.</p>"; } } else { echo "<p style=\'color:red;\'>Please fill in both fields!</p>"; } } ?> </body> </html> '; preg_match_all($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