What are the potential challenges of running PHP 4 and PHP 5 scripts on separate servers within the same network?

Running PHP 4 and PHP 5 scripts on separate servers within the same network can lead to compatibility issues due to differences in syntax and functionality between the two versions. To solve this problem, you can use a PHP version check within your scripts to ensure that the appropriate version-specific code is executed based on the server's PHP version. 

if (version_compare(PHP_VERSION, '5.0.0', '<')) {
    // PHP 4 specific code
} else {
    // PHP 5 specific code
}

Keywords

PHP 4 PHP 5 compatibility migration network configuration

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