How can PHP developers ensure cross-platform compatibility when dealing with character encoding issues?

Character encoding issues can be mitigated by using the `mbstring` extension in PHP, which provides multi-byte string functions to handle different character encodings. PHP developers can ensure cross-platform compatibility by setting the internal encoding to UTF-8 using `mb_internal_encoding('UTF-8')` and using `mb_convert_encoding()` to convert strings between different encodings.

// Set internal encoding to UTF-8
mb_internal_encoding('UTF-8');

// Convert string from ISO-8859-1 to UTF-8
$utf8String = mb_convert_encoding($isoString, 'UTF-8', 'ISO-8859-1');