PHP随机颜色生成器

function randomColor() { 
    $str = '#'; 
    for($i = 0 ; $i < 6 ; $i++) { 
        $randNum = rand(0 , 15); 
        switch ($randNum) { 
            case 10: $randNum = 'A'; break; 
            case 11: $randNum = 'B'; break; 
            case 12: $randNum = 'C'; break; 
            case 13: $randNum = 'D'; break; 
            case 14: $randNum = 'E'; break; 
            case 15: $randNum = 'F'; break; 
        } 
        $str .= $randNum; 
    } 
    return $str; 
} 
$color = randomColor();