How can PHP code be modified to ensure compatibility with different PHP versions, such as PHP4 and PHP5.2?

To ensure compatibility with different PHP versions such as PHP4 and PHP5.2, it is important to avoid using deprecated functions or features that are no longer supported in newer versions of PHP. One way to achieve this is to use conditional statements to check the PHP version before executing certain code blocks, and to use alternative functions or methods if necessary. 

// Check PHP version and use alternative functions for compatibility
if (version_compare(PHP_VERSION, '5.2.0', '<')) {
    // Code for PHP4
    // Example: mysql_connect() for PHP4
} else {
    // Code for PHP5.2 and above
    // Example: mysqli_connect() for PHP5.2
}

Keywords

PHP version compatibility backward compatibility PHP4 PHP5.2 code modification

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