Bubble array sort in C++ implementation - c++

Question

I'm trying to get this code to sort names but it doesn't seem to work for me. What could be wrong? I have a class named Student and want to pass the names and sort them in ascending order. So what I am trying to do is pass the 4 object firstname onto the the sort_list function and sort them in ascending order and display them afterwards. However when I run the code it shows me the same order I had and the sort function didn't seem to have done anything. See if you guys can help me out here.
#include <iostream>
#include<string>
using namespace std;
//***************************************************************************
//STUDENT CLASS
//***************************************************************************
class Student
{
private:
string firstname;
string lastname;
string studentID;
string phoneNumber;
double gpa;
public:
Student();
Student(const string&, const string&, const string&, const string&, const double&);
string getfirstName() const;
string getlastName() const;
string getstudentId() const;
string getphoneNumber() const;
double getGPA() const;
void setfirstName(string&);
void setlastName(string&);
void setstudentId(string&);
void setphoneNumber(string&);
void setGAP(double&);
};
Student::Student()
{
firstname = " ";
lastname = " ";
studentID = " ";
phoneNumber = " ";
gpa = 0;
}
Student::Student(const string&a, const string&b, const string&c, const string&d, const double&e)
{
firstname = a;
lastname = b;
studentID = c;
phoneNumber = d;
gpa = e;
}
string Student::getfirstName()const
{
return firstname;
}
string Student::getlastName()const
{
return lastname;
}
string Student::getstudentId() const
{
return studentID;
}
string Student::getphoneNumber() const
{
return phoneNumber;
}
double Student::getGPA() const
{
return gpa;
}
void Student::setfirstName(string&u)
{
firstname = u;
}
void Student::setlastName(string&v)
{
lastname = v;
}
void Student::setstudentId(string&x)
{
studentID = x;
}
void Student::setphoneNumber(string&y)
{
phoneNumber = y;
}
void Student::setGAP(double&z)
{
gpa = z;
}
//***************************************************************************
//COURSE CLASS
//***************************************************************************
class Course :public Student
{
private:
string code;
int section;
int capacity;
int numStudents;
Student *list;
public:
Course();
Course(string, int, int);
~Course();
string getCourseCode();
int getSection();
int getCapacity();
int getNumStudents();
void setCourseCode(string);
void setSection(int);
void add(const Student&);
void display();
void display(const string, const int);
void remove(const string m, const int n);
void sort_list();
};
Course::Course()
{
code = "CMPT1020";
section = 1;
capacity = 35;
numStudents = 0;
list = new Student[35];
}
Course::Course(string a, int b, int c)
{
code = a;
section = b;
capacity = c;
numStudents = 0;
list = new Student[c];
}
Course::~Course()
{
delete[] list;
list = nullptr;
}
string Course::getCourseCode()
{
return code;
}
int Course::getSection()
{
return section;
}
int Course::getCapacity()
{
return capacity;
}
int Course::getNumStudents()
{
return numStudents;
}
void Course::setCourseCode(string a)
{
code = a;
}
void Course::setSection(int b)
{
section = b;
}
void Course::add(const Student& s)
{
if (numStudents == capacity)
{
cout << "Course is full" << endl;
return;
}
list[numStudents] = s;
numStudents++;
int i = numStudents - 2;
while (i >= 0 && (s.getGPA() > list[i].getGPA()))
{
list[i + 1] = list[i];
i--;
}
list[i + 1] = s;
}
void Course::display()
{
for (int i = 0; i < numStudents; i++)
{
cout<<list[i].getfirstName() <<" "<< list[i].getlastName() <<" "<< list[i].getstudentId() <<" "<< list[i].getphoneNumber() <<" "<< list[i].getGPA() << endl;
}
}
void Course::display(const string x, const int y)
{
if (y == 1)
{
for (int i = 0; i < numStudents; i++)
{
if (list[i].getfirstName() == x)
{
cout << list[i].getfirstName() << " " << list[i].getlastName() << " " << list[i].getstudentId() << " " << list[i].getphoneNumber() << " " << list[i].getGPA() << endl;
}
}
}
if (y == 2)
{
for (int i = 0; i < numStudents; i++)
{
if (list[i].getlastName() == x)
{
cout << list[i].getfirstName() << " " << list[i].getlastName() << " " << list[i].getstudentId() << " " << list[i].getphoneNumber() << " " << list[i].getGPA() << endl;
}
}
}
if (y == 3)
{
for (int i = 0; i < numStudents; i++)
{
if (list[i].getstudentId() == x)
{
cout << list[i].getfirstName() << " " << list[i].getlastName() << " " << list[i].getstudentId() << " " << list[i].getphoneNumber() << " " << list[i].getGPA() << endl;
}
}
}
if (y == 4)
{
for (int i = 0; i < numStudents; i++)
{
if (list[i].getphoneNumber() == x)
{
cout << list[i].getfirstName() << " " << list[i].getlastName() << " " << list[i].getstudentId() << " " << list[i].getphoneNumber() << " " << list[i].getGPA() << endl;
}
}
}
}
void Course::remove(const string a, const int b)
{
if (b == 1)
{
for (int i = 0; i < numStudents; i++)
{
if (list[i].getfirstName() == a)
{
for (int j = i; j < numStudents; j++)
{
list[j] = list[j + 1];
}
numStudents--;
}
}
}
if (b == 2)
{
for (int i = 0; i < numStudents; i++)
{
if (list[i].getlastName() == a)
{
for (int j = i; j < numStudents; j++)
{
list[j] = list[j + 1];
}
numStudents--;
}
}
}
if (b == 3)
{
for (int i = 0; i < numStudents; i++)
{
if (list[i].getstudentId() == a)
{
for (int j = i; j < numStudents; j++)
{
list[j] = list[j + 1];
}
numStudents--;
}
}
}
if (b == 4)
{
for (int i = 0; i < numStudents; i++)
{
if (list[i].getphoneNumber() == a)
{
for (int j = i; j < numStudents; j++)
{
list[j] = list[j + 1];
}
numStudents--;
}
}
}
}
void Course::sort_list()
{
string temp;
for (int i = 0; i < numStudents; i++)
{
for (int j = 0; j < numStudents-1; j++)
{
if(list[j].getfirstName() >list[j+1].getfirstName())
{
temp = list[j].getfirstName();
list[j].getfirstName() = list[j+1].getfirstName();
list[j+1].getfirstName() = temp;
}
}
}
}
int main()
{
Student a("Kevin", "Chen", "300215915", "7788408028", 2);
Student b("Mickey", "Mouse", "12345678", "2222222222", 2.5);
Student c("Donald", "Duck", "24681012", "3333333333", 3.0);
Student d("Goofy", "Dog", "3579111315", "5555555555", 3.5);
Course x;
x.add(a);
x.add(b);
x.add(c);
x.add(d);
x.display();
cout << endl;
x.sort_list();
x.display();
/*cout << " " << endl;
x.remove("kevin", 1);
x.remove("Chen", 2);
x.remove("300215915", 3);
x.remove("7788408028", 4);
x.display();
cout << endl;
x.display("kevin", 1);
x.display("Mouse", 2);
x.display("24681012", 3);
x.display("5555555555", 4);*/
system("pause");
return 0;
}

Answer 1

It is true that your sorting code doesn't do anything.
Here is the core of it:
temp = list[j].getfirstName();
list[j].getfirstName() = list[j+1].getfirstName();
list[j+1].getfirstName() = temp;
getfirstName() returns the first name by value so all your assignments are doing is swapping temporary copies of the first names. There is no effect on the actual list elements.
I think you meant:
temp = list[j];
list[j] = list[j+1];
list[j+1] = temp;
This also means temp must be declared as a Student, not a std::string.
Also, unless I'm misremembering how Bubble Sort works (which is certainly possible — given its uselessness in the real world, it's been a long time since I've written one), your outer loop needs as many iterations as it takes for the inner loop not to be doing any swaps any more. If that's somehow inherently capped at numStudents iterations, I can't see why, nor see any evidence of it on the Wikipedia article.
Assuming I am on the right lines with that, I'd have the function looking like this:
void Course::sort_list()
{
bool go_again = false;
do {
go_again = false;
for (int i = 0; i < numStudents-1; i++) {
if (list[i].getfirstName() > list[i+1].getfirstName()) {
Student temp = list[i];
list[i] = list[i+1];
list[i+1] = temp;
go_again = true;
}
}
} while(go_again);
}
(live demo)