How can the improper use of iconv() and htmlentities() impact PHP code readability and functionality?

Improper use of iconv() and htmlentities() can impact PHP code readability and functionality by introducing unexpected behavior or errors. To ensure proper usage, it's important to understand the parameters and purpose of these functions. It's recommended to always check the documentation and handle input data appropriately to prevent any issues.

// Fix for proper usage of iconv() and htmlentities()

// Example of proper usage of iconv() to convert encoding
$inputString = "Hello, world!";
$convertedString = iconv("UTF-8", "ISO-8859-1//TRANSLIT", $inputString);

// Example of proper usage of htmlentities() to encode special characters
$specialString = "<script>alert('Hello, world!');</script>";
$encodedString = htmlentities($specialString, ENT_QUOTES);