php get file size from byte

php _get_file_size_from_byte.php

/**
* @param $bytes
* @param string $unit
* @param int $decimals
* @return string
*/
static function sizeFormat($bytes, $unit = "", $decimals = 2)
{
    $units = array('B' => 0, 'KB' => 1, 'MB' => 2, 'GB' => 3, 'TB' => 4, 'PB' => 5, 'EB' => 6, 'ZB' => 7, 'YB' => 8);
    $value = 0;
    if ($bytes > 0) {
        if (!array_key_exists($unit, $units)) {
            $pow = floor(log($bytes)/log(1024));
            $unit = array_search($pow, $units);
        }
        $value = ($bytes/pow(1024,floor($units[$unit])));
    }
    if (!is_numeric($decimals) || $decimals < 0) {
        $decimals = 2;
    }
    return sprintf('%.' . $decimals . 'f '.$unit, $value);
}