GRADEBOOK.h#include <string> // class GradeBook usesC++ standard string classusingstd::string;// GradeBook class definitionclassGradeBook{public:GradeBook(string, string);//constructor that initializes courseName andcourseInstructorNamevoidsetCourseName(string);//function that sets the course namestring getCourseName();// function thatgets the course namevoiddisplayMessage();// function thatdisplays a welcome messagevoidsetCourseInstructorName(string);// b) function that sets the courseinstructor namestring getCourseInstructorName();// b)function that get the course instructornameprivate:string courseName;// course name forthis GradeBookstring courseInstructorName;// a)course instructor name for this GradeBook};// end class GradeBook