C++ Classes, Basic overloading errors - c++

Question

I am trying to make a program that makes a class called student that as a student ID, an array of grades, and a number showing how many grades are in the array. The class is supposed to have member methods that enter a student ID number, enter a single test grade and update the total number of grades entered, and compute an average grade and display the student ID followed by the average grade. Here is my code so far.
#include <iostream>
using namespace std;
class Student
{
public:
int StudentID;
double Grades[5];
int NumberOfGrades;
// Member functions declared here
int setID(int id);
double setGrades(double g[5]);
double getAverage(void);
};
// make them functions work, son.
int Student::setID(int ID)
{
cout << "Please enter in the student's ID number: ";
cin >> ID;
return 0;
}
double Student::setGrades(double g[5])
{
for (int i = 0; i < 5; i++)
{
cout << "Please enter in grade number " << i ;
cin >> g[i];
NumberOfGrades++;
}
return 0;
}
double Student::getAverage(void)
{
int sum = 0,average; // declare what I need in average
for (int i = 0; i < 5; i++)
{
sum = sum + Grades[i];
}
average = sum / NumberOfGrades;
cout << "The average for " << StudentID << " is " << average;
return 0;
}
int main ()
{
Student Student1;
Student1.setID; // error
Student1.setGrades; // error
Student1.getAverage();
}
I am getting the error saying that it cannot resolve the address of overloaded function. Can someone explain to me what an overloaded fuction is, in simplest terms possible? Also, if possible, could anyone explain why I got that error in my code?

Answer 1

First of all, you need to actually call these functions:
Student1.setID -> Student1.setID()
Student1.setGrades -> Student1.setGrades()
That's not enough, though, these function require arguments (int and double[5], respectively). So:
int id = 65;
double grades[5] = { 3.5, 4.0, 4.0, 3.0, 4.5 };
Student1.setID(id);
Student1.setGrades(grades);
This will only remove compiler errors, though. Perhaps you don't see this, but your functions are implemented incorrectly:
int Student::setID(int ID)
{
cout << "Please enter in the student's ID number: ";
cin >> ID; //you fill ID, which is a temporary variable!
return 0;
}
Also, if you ask user inside setID() for id, what is the purpose of this parameter? Remove it - change setID(int ID) to setID():
int Student::setID()
{
int input_id;
cout << "Please enter in the student's ID number: ";
cin >> input_id;
this->StudentID = input_id;
return 0;
}

Answer 2

I see a few major problems with the code:
int Student::setID(int ID)
{
cout << "Please enter in the student's ID number: ";
//ID is local. Assigning any value to it will have no effect on the class
cin >> ID;
//You might as well not return anything if the function is purely impure
return 0;
}
The other issue is a "setter" shouldn't be taking input from a user, and doing an assignment; those are 2 separate tasks. I'd set up this function as:
void Student::setID(int ID)
{
StudentID = ID;
}
Notice that we're assigning to the StudentID a value passed in as an argument. Use like:
//In main
Student student;
int newStudentID = 1234;
student.setID(newStudentID);