There is a mistake on the "Download documentation".(The download version, like http://sg.php.net/distributions/manual/manual-en.chm
)
In the download documentation,there is a mistake in the "array_keys".

The origin on the documentation is:

Example 2. Implementation of array_keys() for PHP 3 users 
function array_keys ($arr, $term="") {
    $t = array();
    while (list($k,$v) = each($arr)) {
        if ($term && $v != $term) {
            continue;
            $t[] = $k;
        }
        return $t;
    }
}

I think it should be 
function array_keys ($arr, $term="") {
    $t = array();
    while (list($k,$v) = each($arr)) {
        if ($term && $v != $term) {
            continue;
        }
        $t[] = $k;
    }
    return $t;
}

Online documentation do not have such problem.