What is the difference between htmlspecialchars() and htmlentities() functions in PHP and how can they be used to prevent unwanted character conversions?

The issue is preventing unwanted character conversions, such as special characters like <, >, &, and ". htmlspecialchars() and htmlentities() are PHP functions that can be used to encode these characters to prevent XSS attacks. To prevent unwanted character conversions, you can specify the encoding parameter in htmlspecialchars() or htmlentities() to ensure that the characters are converted correctly.

// Using htmlspecialchars() with specified encoding to prevent unwanted character conversions
$text = "<h1>Hello, world!</h1>";
echo htmlspecialchars($text, ENT_QUOTES, 'UTF-8');