Compare Class Object using bubble sort - c++

Question

Task: Model in OOP a class named Student containing name, surname and the marks from the winter session exams. Display the name of the students who have arrears exams and the first three students in the group.
I have troubles in comparing the marks(first three students).
My code:
#define _CRT_SECURE_NO_WARNINGS
#include<iostream>
using namespace std;
#include <string>
#include<stdio.h>
class Student {
private:
char nume[10];
char prenume[20];
double matematica;
double fizica;
double programare;
public:
Student(char num[10], char pren[20], double mate, double fiz, double progra);
void afis();
void citire_stud();
int restanta();
double media();
};
Student::Student(char num[10] = "", char pren[20] = "", double mate = 0, double fiz = 0, double progra = 0)
{
strcpy(nume, num);
strcpy(prenume, pren);
matematica = mate;
fizica = fiz;
programare = progra;
}
void Student::afis()
{
cout << "Nume: " << nume << endl;
cout << "Prenume: " << prenume << endl;
cout << "Nota la matematica: " << matematica << endl;
cout << "Nota fizica: " << fizica << endl;
cout << "Nota programare: " << programare << endl;
cout << endl;
}
void Student::citire_stud()
{
char num[10];
char pren[20];
double mate, fiz, progra;
cout << "Introduceti numele studentului: " << endl;
cin >> num;
strcpy(nume, num);
cout << "Introduceti preumele studentului: " << endl;
cin >> pren;
strcpy(prenume, pren);
cout << "Introduceti nota la mate studentului: " << endl;
cin >> mate;
matematica = mate;
cout << "Introduceti nota la fizica studentului: " << endl;
cin >> fiz;
fizica = fiz;
cout << "Introduceti nota la programare studentului: " << endl;
cin >> progra;
programare = progra;
}
int Student::restanta() //arrears
{
if (matematica < 5 || programare <5 || fizica < 5)
return 1;
else return 0;
}
double Student::media()
{
double med;
med = (matematica + fizica + programare) / 3;
return med;
}
void main()
{
int cont = 0;
int res[10];
int nr;
cout << "Cati studenti sunt(max 10): "; //How many students
cin >> nr;
Student ob2[10], temp;
for (int i = 0;i < nr;i++)
{
ob2[i].citire_stud();
if (ob2[i].restanta())
{
res[cont++] = i;
}
}
if (cont == 0)
{
cout << "Nu sunt studenti restanti! " << endl;
goto jmp;
}
else
{
cout << "\nStundetii restanti sunt: " << endl;
int i = 0;
int k = 0;
do
{
k = res[i];
ob2[k].afis();
i++;
} while (i != cont);
}
jmp:
cout << "\n\n\n\nStudentii in ordinea medilor sunt: " << endl;
for (int i = 0;i < nr;i++)
{
if (ob2[i].media() < ob2[i + 1].media()) //Not working
{
temp = ob2[i];
ob2[i] = ob2[i + 1];
ob2[i + 1] = temp;
}
}
for (int i = 0;i < nr;i++)
ob2[i].afis();
system("pause");
}
Output: Output
It should be: 9 - 7 - 5

Answer 1

Your bubble sort is broken. A) You need 2 loops. B) you go out of bounds. Change it to something like:
for (int j = 0; j < nr; j++)
{
for (int i = 0;i < nr - 1 ; i++)
{
if (ob2[i].media() < ob2[i + 1].media())
{
temp = ob2[i];
ob2[i] = ob2[i + 1];
ob2[i + 1] = temp;
}
}
}