说明：  在C++中open一個output file有兩種方式，一種是使用member function open( )，另外一種是使用constructor給予檔案名稱和open mode。今若欲open一個名為client.dat的output file，試分別寫出該兩種方式open此檔案的statements.(包括include header file，物件的宣告，open指令等)
(In the C++ In open an output file in two ways, one is to use the member function open (), another is to use the constructor to give the file name and open mode. This wants to open a client.dat the output file, write the test, respectively, open this file in two ways the statements. (Including the include header file, object declaration, open orders, etc.))