tYSR20

176Part III: Introduction to ClassesNormally the :: operator is optional, but there are a few occasions when thisis not so, as illustrated here:// addCourse - combine the hours and grade into// a weighted gradefloat addCourse(int hours, float grade){return hours * grade;}class Student{public:int semesterHours;float gpa;// add a completed course to the recordfloat addCourse(int hours, float grade){// call some external function to calculate the// weighted gradefloat weightedGPA = addCourse(semesterHours, gpa);// now add in the new coursesemesterHours += hours;// use the same function to calculate the weighted// grade of this new courseweightedGPA += addCourse(hours, grade);gpa = weightedGPA / semesterHours;};}// return the new gpareturn gpa;Here, I want the member function Student::addCourse() to call the nonmemberfunction ::addCourse(). Without the :: operator, however, a callto addCourse() from Student refers to Student::addCourse().One member of the family can use the short name when referring to anothermember of the same family. The family . . . I mean class name . . . is understood.Not indicating the class name in this case results in the function calling itself,which is generally not a good thing. Adding the :: operator to the frontdirects the call to the global version, as desired: