PHP quirks and pitfalls [closed]

Answer 1

== EDIT == This is no longer true for PHP >= 5.5!

What I sometimes run into is the Fatal error: Can't use function return value in write context error when using the empty() construct. For example:

if (!empty(trim($_GET['s']))) {
    // ...
}

empty() needs a variable, anything else will result in the error.

The solution:

$s = trim($_GET['s']);
if (!empty($s)) {
    // ...
}