假如中d根目录下存在一个a.txt文件,执行下面程序,结果是: public static void Main() { if (File.Exists("d:\\a.txt")) System.Console.WriteLine("ok1"); if (Directory.Exists("d:\\a.txt")) System.Console.WriteLine("ok2"); FileInfo fi = new FileInfo("d:\\a.txt"); DirectoryInfo di = new DirectoryInfo("d:\\a.txt"); if (fi.Exists) System.Console.WriteLine("ok3"); if (di.Exists) System.Console.WriteLine("ok4"); }