How can PHP developers ensure backward compatibility when transitioning from PHP 4 to PHP 5?

To ensure backward compatibility when transitioning from PHP 4 to PHP 5, PHP developers can update their code to adhere to the new features and syntax introduced in PHP 5 while also maintaining support for PHP 4. This can be achieved by using conditional statements to check the PHP version and implementing alternative code paths based on the version detected. 

if (version_compare(PHP_VERSION, '5.0.0', '>=')) {
    // PHP 5 code here
} else {
    // PHP 4 code here
}

Keywords

PHP 4 PHP 5 backward compatibility deprecated functions migration

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