What are the potential pitfalls of upgrading from PHP 4.3.1 to PHP 5 on a Suse Linux server?

Upgrading from PHP 4.3.1 to PHP 5 on a Suse Linux server may lead to compatibility issues with existing code and applications that rely on deprecated features or syntax. It is important to thoroughly test the upgraded code to ensure compatibility and make necessary adjustments to ensure proper functionality.

// Example code snippet for upgrading from PHP 4.3.1 to PHP 5

// Replace deprecated functions with their updated equivalents
// For example, replace ereg() with preg_match()

// Before
if (ereg('pattern', $string)) {
    // do something
}

// After
if (preg_match('/pattern/', $string)) {
    // do something
}