按时间条件删除文件和文件夹

private static void FindFiles(string filepath)
{
if(filepath!=null)
{
DirectoryInfo di = new DirectoryInfo(filepath);
if(di!=null)
{
FileInfo[] files = di.GetFiles("*.cs",SearchOption.AllDirectories);
foreach(FileInfo fi in files)
{
DateTime filect = fi.CreationTime;                        
if(DateTime.Now.Subtract(filect).TotalSeconds>=10)
{
fi.Delete();
}
}
}
}       
}

private static void FindFiles(string filepath)