How can PHP developers ensure that special characters are displayed correctly in their applications, especially when dealing with different character sets?

Special characters can be displayed correctly in PHP applications by ensuring that the appropriate character encoding is set and consistent throughout the application. Developers can use functions like htmlentities() or htmlspecialchars() to encode special characters before displaying them on the webpage. Additionally, setting the correct meta tag for character encoding in the HTML header can help ensure that special characters are displayed correctly.

<?php
// Set the character encoding
header('Content-Type: text/html; charset=UTF-8');

// Encode special characters before displaying them
$special_string = "Special characters like & < > ' \" are encoded";
echo htmlentities($special_string);
?>