What are the differences between htmlentities() and htmlspecialchars() functions in PHP when converting special characters to HTML entities?

When converting special characters to HTML entities in PHP, htmlentities() and htmlspecialchars() functions are commonly used. The main difference between the two functions is that htmlentities() converts all applicable characters to HTML entities, while htmlspecialchars() only converts characters that have special meaning in HTML (like <, >, ", ', and &). If you need to encode all characters, including those that don't have special meaning in HTML, use htmlentities(). If you only need to encode characters with special meaning in HTML, use htmlspecialchars().

// Using htmlentities() to convert all characters to HTML entities
$string = "This is a <b>bold</b> statement";
$encoded_string = htmlentities($string);
echo $encoded_string;

// Using htmlspecialchars() to convert only special characters to HTML entities
$string = "This is a <b>bold</b> statement";
$encoded_string = htmlspecialchars($string);
echo $encoded_string;