PHP三元运算符给出了意想不到的T_echo

My ternary is returning an error. Am I forgetting some basic rule or quirk about using PHP ternaries with echos?

isset($tag) ? 
    echo '<a href="#">' . $tag['firstname'] . '</a>' : null;

The above ternary returns the following error:

Parse error: syntax error, unexpected T_ECHO in /classes/Photo.php on line 216

you should write like this:

echo (isset($tag) ? '<a href="#">' . $tag['firstname'] . '</a>' : '');

Use print() instead of echo when you need to display text within an expression.