Question

1. Write the header and the implementation files (.h and .cpp separately) for a class called Course, and a simple program to test it (C++), according to the following specifications:                   

1. Your class has 3 member data: an integer pointer that will be used to create a dynamic variable to represent the number of students, an integer pointer that will be used to create a dynamic array representing students’ ids, and a double pointer that will be used to create a dynamic array to represent the GPAs of each student.

2. Your class has the following member functions:

       

1. a constructor with an int parameter representing the number of students; the constructor creates the dynamic variable and sets it to the int parameter, creates the two dynamic arrays and sets everything to zero.

2. a function which reads in all the ids and the GPAs into the appropriate arrays.

3. a function called print_info which, for each student, does all of the

                following:

                It prints the student’s id and GPA. If the student’s GPA is greater than or equal to 3.8, it prints “an honor student”.

4. a destructor (hint: delete array)
5. create 5 random instances of Course objects to represents 5 sessons of CSC211, each session includes 20 students, assign random score to each student, calculate the average GPA of all 100 students.

Answer 1

Ans: Since It is not specified in the question hence all the data members are declared as private and an extra utility function to get average of GPA per course has been created. Alternative to this is declare gpa array as public and calculating average in the main function.

Also, assignRandom function is created just to populate the values in each instance of the class and hence it is not an essential function.

Note: Read comments in the code to get it's description.

#include<bits/stdc++.h>
using namespace std;

// Course Class
class Course{
    private:
        int* number_of_students;
        int* sId;
        double* gpa;

    public:
        // Constructor dynamically assigns memory
        Course(int student_count){
            number_of_students = new int;
            *number_of_students = student_count;

            sId = (int*)malloc(sizeof(int)*student_count);
            gpa = (double*)malloc(sizeof(double)*student_count);

            for(int i = 0; i<student_count; i++){
                sId[i] = 0;
                gpa[i] = 0;
            }
        }

        // Function to add students at the end in a particular course
        void enroll(int Id, double gpa_score){
            int i = 0;

            while(i<*number_of_students && sId[i] != 0)
                i++;

            // If no more students can be added then return
            if(i == *number_of_students)
                return;
            
            sId[i] = Id;
            gpa[i] = gpa_score;
        }

        // Function prints the required info per course
        void print_info(){
            int n = *number_of_students;

            for(int i = 0; i<n; i++){
                cout<<sId[i]<<"\t"<<gpa[i]<<"\t";
                if(gpa[i] >= 3.8)
                    cout<<"An honor student";
                cout<<"\n";
            }
        }

        // Returns the average value of GPA in a particular course
        double getAverage(){
            double sum = 0.0;
            for(int i = 0; i<*number_of_students; i++)
                sum += gpa[i];

            return sum/(*number_of_students);
        }

        // Destructor function
        ~Course(){
            delete (number_of_students);
            delete [] sId;
            delete [] gpa;
        }
};


// Utility function to assign random values to the instance of the course class
Course * assignRandom(Course* obj, int size){
    int id;
    double gpa;

    for(int i = 0; i<size; i++){
        id = (rand()%100)+1;
        gpa = (rand()%5)+1;
        gpa = gpa+(id/100.0);

        obj->enroll(id, gpa);
    }
    return obj;
}

// Driver function
int main(){

    Course *c1 = new Course(20);
    Course *c2 = new Course(20);
    Course *c3 = new Course(20);
    Course *c4 = new Course(20);
    Course *c5 = new Course(20);

    c1 = assignRandom(c1, 20);
    c1->print_info();
    cout<<"\n";

    c2 = assignRandom(c2, 20);
    c2->print_info();
    cout<<"\n";

    c3 = assignRandom(c3, 20);
    c3->print_info();
    cout<<"\n";

    c4 = assignRandom(c4, 20);
    c4->print_info();
    cout<<"\n";

    c5 = assignRandom(c5, 20);
    c5->print_info();
    cout<<"\n";

    // Calculating and printing overall GPA
    double overAllGpa = (c1->getAverage()+ c2->getAverage() + c3->getAverage() + c4->getAverage() + c5->getAverage())/5;

    cout<<"OverAll average GPA: "<<overAllGpa<<"\n";

    return 0;
}