What are some common encoding issues that PHP developers may encounter when working with external data sources?

One common encoding issue PHP developers may encounter when working with external data sources is mismatched character encodings. This can result in garbled text or special characters not displaying correctly. To solve this issue, developers can convert the encoding of the external data to match the encoding used in their PHP application.

// Convert external data encoding to match PHP application encoding
$externalData = mb_convert_encoding($externalData, 'UTF-8', 'ISO-8859-1');