How to Define CountProbation() function using Functions from other Files? - c++

Question

I have been racking my brain on how to properly define the function CountProbation() properly in the Course.css file. I know that a for and if loop should probably be included but I am having trouble including functions from other files, even though I am including a header tag at the beginning of the current Course.css file.
Below are the C++ files that are given in the lab:
NOTE: Only the Course.cpp file is the one that needs to be edited. All of the other files are READ ONLY and purely for your information as the reader.
Sorry if it seems like a lot of code, but I didn't just want to include the Course.cpp file because then you might not understand the program.
Here are the compiler Errors/Warnings:
Course.cpp: In member function ‘int Course::CountProbation()’:
Course.cpp:8:18: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<Student>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
8 | for (int i=0; i < roster.size(); ++i) {
| ~~^~~~~~~~~~~~~~~
Course.cpp:9:9: error: ‘GetGPA’ was not declared in this scope
9 | if (GetGPA() < 2.0) {
| ^~~~~~
Course.cpp
#include <iostream>
#include "Course.h"
#include "Student.h"
using namespace std;
int Course::CountProbation() { //This is the function that I have tried to define as you can see by my
int probCount; //code
for (int i=1; i < roster.size(); ++i) {
if (GetGPA() < 2.0) {
probCount = probCount + 1;
}
}
return probCount;
}
void Course::AddStudent(Student s) {
roster.push_back(s);
}
Course.h (READ ONLY)
#ifndef COURSE_H
#define COURSE_H
#include <vector>
#include "Student.h"
class Course {
public:
int CountProbation();
void AddStudent(Student s);
private:
vector<Student> roster; //collection of Student objects
};
#endif
Main.cpp (READ ONLY)
#include <iostream>
#include <string>
#include "Course.h"
using namespace std;
int main() {
Course course;
int probCount;
// Example students for testing
course.AddStudent(Student("Henry", "Cabot", 3.2));
course.AddStudent(Student("Brenda", "Stern", 1.1));
course.AddStudent(Student("Lynda", "Robison", 2.4));
course.AddStudent(Student("Jane", "Flynn", 1.8));
probCount = course.CountProbation();
cout << "Probation count: " << probCount << endl;
return 0;
}
Student.h (READ ONLY)
#ifndef STUDENT_H
#define STUDENT_H
#include <string>
using namespace std;
// Class representing a student
class Student {
public:
Student(string first, string last, double gpa);
double GetGPA() ;
string GetLast();
private:
string first; // first name
string last; // last name
double gpa; // grade point average
};
#endif
Student.cpp (READ ONLY)
#include "Student.h"
// Student class constructor
Student::Student(string first, string last, double gpa) {
this->first = first; // first name
this->last = last; // last name
this->gpa = gpa; // grade point average
}
double Student::GetGPA() {
return gpa;
}
string Student::GetLast() {
return last;
}

Answer 1

This loop (as it was coded in the original question, before it was edited):
for (int i=1; i < roster.size(); ++i) {
if (Student.GetGPA() < 2.0) {
probCount = probCount + 1;
}
}
is flawed for three reasons:
i should start from 0, rather than 1
i should be of type size_t, rather than int
Student is a type, not a variable
A nice way to solve all these problems is to use a ranged for loop, like this:
for (Student &student : roster)
{
if (student.GetGPA() < 2.0)
probCount = probCount + 1;
}
As mentioned in the comments, you also need to initialise probCount to zero before entering the loop:
int probCount = 0;
Finally, it's worth noting that the above loop would normally be coded as:
for (const Student &student : roster)
{
...
but that won't work here as GetGPA is not declared as a const method. Thanks to #user4581301 for pointing this out.