可读性文件尺寸

/**
 * 返回可读性更好的文件尺寸
 */
function human_filesize($bytes, $decimals = 2)
{
    $size = ['B', 'kB', 'MB', 'GB', 'TB', 'PB'];
    $factor = floor((strlen($bytes) - 1) / 3);

    return sprintf("%.{$decimals}f", $bytes / pow(1024, $factor)) .@$size[$factor];
}