PHP 5.5: What's New, Release History & EOL Status

What Is New in PHP 5.5

PHP 5.5 delivers a significant upgrade with new language features, performance improvements, and the removal of legacy functionality. This release focuses on modernizing the language for more expressive and efficient code.

What are the major new language features?

Generators are the standout feature, introducing a simple way to implement iterators without the overhead of a full class. You use the yield keyword to provide values to a foreach loop on the fly.

function numberGenerator() {
    for ($i = 0; $i < 5; $i++) {
        yield $i;
    }
}

foreach (numberGenerator() as $number) {
    echo $number;
}

The finally block brings PHP's exception handling in line with other languages, guaranteeing that a block of code will run after a try, regardless of whether an exception was thrown or caught.

How did password handling improve?

PHP 5.5 introduced a dedicated, simple, and secure API for password hashing. The new functions password_hash() and password_verify() abstract away the complexity of salting and using strong algorithms like BCrypt.

// Hashing a password
$hash = password_hash('my_password', PASSWORD_DEFAULT);

// Verifying a password
if (password_verify('my_password', $hash)) {
    // Password is valid
}

This was a huge win for security, making it much harder for developers to incorrectly implement password storage. The old methods involving md5() or sha1() became instantly obsolete.

What performance enhancements were made?

The most significant performance boost came from bundling the Zend OPcache extension directly into the core and enabling it by default. OPcache stores precompiled script bytecode in shared memory, eliminating the need for PHP to load and parse scripts on every request.

This change drastically reduced CPU usage and improved throughput for most applications. For many, simply upgrading to 5.5 provided a free speed upgrade without any code changes.

What was deprecated and removed?

This release continued the push to clean up old cruft. The original mysql extension was officially deprecated, urging developers to move to mysqli or PDO. The preg_replace /e modifier was also deprecated due to its security implications.

Support for older Windows operating systems (XP and 2003) was dropped, allowing the core team to focus on modern platforms. This cleanup is a necessary part of keeping the language modern and maintainable.