overloaded assignment operator not working - c++

Question

I have a class Employee. (Some of my comments are not updated from when I added members tasks and taskList; I apologize for that.)
Employee.h
#include <string>
#include <iostream>
using namespace std;
class Employee {
private:
string employee_name;
string employee_ssn;
string * taskList; //stores an array of tasks for the employee to do
int tasks; //stores the number of tasks an employee needs to do
public:
//constructors
Employee(); //default - nothing
Employee(string, string, string a[], int numOfTasks); //sets both ssn and name
~Employee(); //destructor
//copy constructor:
Employee(const Employee &emp);
Employee & operator =(const Employee& source);
void set_name(string); //sets name in program
void set_ssn(string); //sets ssn in program
string get_ssn(); //returns ssn as string
string get_name(); //returns emp name as string
void display(); //displays both on two separate lines
};
Employee.cpp
#include "Employee.h"
//constructors
//default constructor makes the object empty
Employee::Employee() {
taskList = nullptr;
return;
}
//constructor sets both name and ssn
Employee::Employee(string x, string y, string a[], int numOfTasks) {
employee_name = x;
employee_ssn = y;
tasks = numOfTasks;
taskList = a;
return;
}
//destructor
Employee::~Employee() {
delete [] taskList;
}
//copy constructor
Employee::Employee(const Employee & source) {
//copy simple member variables
employee_name = source.employee_name;
employee_ssn = source.employee_ssn;
tasks = source.tasks;
//allocate new dynamic array for taskList
taskList = new string[source.tasks];
//copy values from one taskList to another
for (int i = 0; i < tasks; i++)
taskList[i] = source.taskList[i];
return;
}
//assignment operator overloading
Employee & Employee::operator =(const Employee& source) {
cout << "Calling the assignment operator overloader.\n";
//check for self assignment
if (this == &source)
return *this; //avoid doing extra work
employee_name = source.employee_name;
employee_ssn = source.employee_ssn;
tasks = source.tasks;
cout << "Substituting 'task list'\n";
//delete former taskList
//if (taskList != nullptr)
delete[] taskList;
cout << "TaskList deleted.\n";
//allocate new one with same capacity
taskList = new string[source.tasks];
//copy values from one to the oher
for (int i = 0; i < tasks; i++)
taskList[i] = source.taskList[i];
cout << "Function complete.\n";
return *this;
}
//postcon: name is set to inputted string
void Employee::set_name(string s) {
employee_name = s;
return;
}
//postcon: ssn is set to inputted string
void Employee::set_ssn(string s) {
employee_ssn = s;
return;
}
//returns ssn as string
string Employee::get_ssn() {
return employee_ssn;
}
//returns employee name as string
string Employee::get_name() {
return employee_name;
}
//precon: name and ssn are both assigned
//postcon: name and ssn printed to the screen w/ labels on two lines
void Employee::display() {
cout << "Name: " << employee_name << endl;
cout << "SSN: " << employee_ssn << endl;
cout << "Tasks:\n";
for (int i = 0; i < tasks; i++)
cout << i + 1 << ". " << taskList[i] << endl;
return;
}
We were instructed to implement a copy constructor and assignment overloading, and we were also specifically instructed to make individual Employee objects dynamically allocated in the main program.
What I seem to be having issue with is the swapping using the assignment overload.
employee_driver.cpp
#include "Employee.h"
#include <iostream>
int main() {
//tasks for each employee to do:
//Tasks to be assigned to Marcy:
string tasks[2] = {"Send emails", "Prepare meeting brief"};
//Taks to be assigned to Michael:
string tasks2[3] = {"Stock up on pens", "Send emails", "Organize union"};
Employee *emp1 = new Employee("Marcy", "678091234", tasks, 2);
Employee *emp2 = new Employee("Michael", "123994567", tasks2, 3);
//display data before swap
emp1->display();
cout << endl;
emp2->display();
cout << endl;
//swap employees
Employee temp(*emp1); //using copy constructor to copy first employee into temporary
*emp1 = *emp2;
*emp2 = temp; //uses overloaded assignment operator to copy values of temp into emp2; Marcy's data is now in Michael's pointer
//display after swap
cout << "\n\nAfter swap:\n\n";
emp1->display();
cout << endl;
emp2->display();
//free heap
delete emp1;
delete emp2;
//delete emp3;
return 0;
}
The issue in question seems to occur here:
*emp1 = *emp2; (towards the bottom of the main program), but I cannot figure out why; any help would be appreciated. I could get around it, but I don't think that's the purpose of the exercise, and I would like to know why this statement is not working correctly.
Thanks.

Answer 1

Within the constructor
Employee::Employee(string x, string y, string a[], int numOfTasks) {
employee_name = x;
employee_ssn = y;
tasks = numOfTasks;
taskList = a;
return;
}
you just store the passed pointer a in the data member taskList,
In main the arrays
string tasks[2] = {"Send emails", "Prepare meeting brief"};
//Taks to be assigned to Michael:
string tasks2[3] = {"Stock up on pens", "Send emails", "Organize union"};
were not allocated dynamically. So you may not in the copy assignment operator call the operator delete [] for such arrays
delete[] taskList;
You need in the constructor to allocate dynamically the array a pointer to which is passed as an argument to the constructor.
Also pay attention to that in the default constructor you need to set the data member tasks to 0.