PHP取出素数并且求和

//PHP取出素数并且求和
 1 function primes($n,$s = false) {
    $primes = array_fill(2,$n - 1,'prime');
    for ($i = 2,$range = intval(sqrt($n)); $i < $range ;$i++) {
        if ( !empty($primes[$i]) ) {
            foreach ($primes as $key => $item) {
                for ($j = 2 * $i; $j <= $n; $j += $i) {
                    unset($primes[$j]);
                }
            }
        }
    }

    $primes = array_keys($primes);
    if ($s) {
        $sum = 0;
        foreach ($primes as $k => $v) {
            $sum += $v;
        }
        $primes['sum'] = $sum;
    }
    print_r($primes);
}

primes(100,true);