定义一个大学生类Graduate，保护数据成员：姓名，学号，校名，并为它定义带参数的构造函数、拷贝构造函数、析构函数和输出数据成员值的print( )公有成员函数，另定义研究生类Postgraduate，它以公有继承方式派生于类Graduate，新增加“研究方向、导师名”两个私有数据成员，并定义带参数的构造函数，拷贝构造函数、析构函数和输出研究生数据的print( )公有成员函数，另外，要求学号自动增加，且Graduate和Postgraduate的学号起始值不同。在主函数中定义派生类对象进行测试。(字符串用char*表示)-Students define a category of Graduate, the protection of data members: name, school number, school name, and with the definition of parameters for its constructor, copy constructor, destructor and member of the value of output data print () public member functions, and the other definition of Graduate Class of Postgraduate, it derived from the public inheritance category Graduate, a new " research, mentor of the"　two private data members, and define the parameters with the constructor, copy constructor, destructor, and print data output Graduate () public member function In addition, the request automatically increase its school, and Graduate and Postgraduate Student of the different start value. In the main function defined in derived class object to be tested. (Char* string with that)