Question

If I have a short function that opens a file and reads a line, do I need to close the file? Or will PHP do this automatically when execution exits the function and $fh is garbage collected?

function first_line($file) {
    $fh = fopen($file);
    $first_line = fgets($fh);
    fclose($fh);
    return $first_line;
}

could then be simplified to

function first_line($file) {
    return fgets(fopen($file));
}

This is of course theoretical right now, as this code doesn’t have any error handling.

Answer 1

PHP automatically runs the resource destructor as soon as all references to that resource are dropped.

As PHP has a reference-counting based garbage collection you can be fairly sure that this happens as early as possible, in your case as soon as $fh goes out of scope.

Before PHP 5.4 fclose didn’t actually do anything if you tried to close a resource that had more than two references assigned to it.