How can PHP developers ensure compatibility with older PHP versions, such as 5.2, while transitioning to newer versions like PHP 7?

To ensure compatibility with older PHP versions like 5.2 while transitioning to newer versions like PHP 7, developers can use conditional statements to check the PHP version and adjust their code accordingly. This can involve using functions or features that are available in both the older and newer versions of PHP, or providing alternative code paths for different PHP versions.

if (version_compare(PHP_VERSION, '7.0.0', '<')) {
    // Code for PHP versions older than 7.0.0
} else {
    // Code for PHP 7 and newer versions
}