What are the key differences between POSIX-extended regular expressions and Perl-compatible regular expressions in PHP?

POSIX-extended regular expressions and Perl-compatible regular expressions have some key differences in syntax and features. POSIX-extended regular expressions are more limited in terms of functionality and do not support advanced features like lookaheads, lookbehinds, and named capture groups. On the other hand, Perl-compatible regular expressions provide a more powerful and flexible syntax with support for these advanced features. To use Perl-compatible regular expressions in PHP, you can make use of the `preg` functions (e.g., `preg_match`, `preg_replace`) instead of the POSIX functions (e.g., `ereg`, `ereg_replace`). By using the `preg` functions with the appropriate flags, you can leverage the full power of Perl-compatible regular expressions in your PHP code. 

// Using Perl-compatible regular expressions in PHP
$string = "Hello, World!";
if (preg_match('/^Hello, (\w+)!$/', $string, $matches)) {
    echo "Match found: " . $matches[1];
} else {
    echo "No match found.";
}

Keywords

POSIX extended regular expressions Perl-compatible regular expressions PHP differences

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