關於class GradeBook

#include <iostream>

using std::cout;
using std::endl;

class GradeBook
{
public:
void displayMessage()
{
cout << "Welcome to the Grade Book!"<< endl;
}
};

int main()
{
GradeBook myGradeBook;
myGradeBook.displayMessage();

return 0;
}


請問以上的class GradeBook有什麼功用?