2.　　创建一个Message类，其构造函数带有一个string类型的默认参数。创建一个string类型的私有成员，在构造函数中只是简单地把参数赋值给内部的私有成员。创建两个重载的成员函数print() ，一个不带参数，而只是显示存储在对象中私有成员的信息，另一个带有string类型参数，它将显示该参数加上对象内私有成员的信息。- Create a macro was not found, the constructor moves with a type of default parameters. Create a type of private members, moves in the constructor simply put the parameter to internal private members. Create two overloaded member function locate 14, 20: print (), Don t take a parameter, and only show stored in the object of private information, another type parameters, it moves with the parameters of the objects that will add private members within the information.