How do you cut off text after a certain amount of characters in PHP?

May I make a modification to pallan's code?

$truncated = (strlen($string) > 20) ? substr($string, 0, 20) . '...' : $string;

This doesn't add the '...' if it is shorter.

Really quickly,

$truncated = substr('12345678901234567890abcdefg', 0, 20) . '...'