Question

Is this possible? I see some native php functions can do that. For example: strpos() can return 0 which can apparently be true.

Answer 1

Edit

When the manual says some function can return both integer 0 and boolean false, it means it can return either integer 0 or boolean false (not both) in any given call. PHP is not strictly typed, functions can return different types in different situations. For instance, the following function returns either 0 or false, depending on whether the passed parameter is non negative or not:

function myfunc($arg) {
    if ($arg >= 0)
        return 0;
    else
        return false;
}

Original

PHP has no multiple return. You have two options:

Return composite values instead

function myfunc() {
    return array(0, true); //return array
}

class MyOutputHolder {
    private $number;
    private $truth;
    function getNumber { return $this->number; }
    function getTruth { return $this->truth; }
    function __construct($number, $truth) {
        $this->number = $number;
        $this->truth = $truth;
    }
}
function myfunc() {
    return new MyOutputHolder(0, true); //return object
}

A third possibility is a custom resource, but that must be implemented internally (in an extension).

Use output parameters

function myfunc(&$outnumber, &$outtruth) {
    $outnumber = 0;
    $outtruth = true;
}

Of course, you can return only 0 or true and use only one parameter.