What strategies can be employed to preserve the functionality of smiley images in a guestbook while preventing them from being broken by long strings of text?

To preserve the functionality of smiley images in a guestbook while preventing them from being broken by long strings of text, you can limit the maximum length of the text input and also escape any HTML characters to prevent injection attacks.

// Limit the maximum length of the text input
$max_length = 100;
$text = substr($text, 0, $max_length);

// Escape HTML characters
$text = htmlspecialchars($text);

// Display the text with smiley images
echo nl2br($text);