Overloading operators

[ZeroesAndOnes]

Hello folks, why in the function 'addTwo' in both cases variable salary equals to 400, independent of the variable passed to the constructor in the main function.

#include <iostream>
using namespace std;


class Employee{
	private:
		int idNum;
		double salary;
	public:
		Employee(int, double);
		double addTwo(Employee);
};
Employee::Employee(int id, double sal)
{
	idNum = id;
	salary = sal;
}
double Employee::addTwo(Employee emp)
{
	double total;
	cout << emp.salary << endl;
	total = salary + emp.salary;
	cout << salary << endl;
	return total;
}
int main(void)
{
	Employee clerk(1234, 400.);
	Employee driver(3456, 650.);
	double sum;
	sum = clerk.addTwo(driver);
	sum = clerk.addTwo(clerk);
	return 0;
}

[GReaper]

Be more specific please. What did you expect to happen and didn't?

[Guest]

I can only assume that you intended to write lines 31 and 32 differently. Otherwise, specify how the output and your expectations differ, as GReaper suggested. In my experience, trying to explain the issue to others will lead you to the solution all by yourself in many cases. I've abandoned countless questions before posting them, because I figured it out while writing.

[sean_cantab]

1. Please initialize variables like total and sum upon declaration, otherwise you have no idea what value's in them before you start using them;

2. In addTwo() the second cout<< should be total, not salary, to give you what you're looking for;

3. The 2 sums you run in main() add (a) salary of driver to that to clerk and (b) salary of clerk to that of itself - are you sure that's what you want or should it be:

    sum = clerk.addTwo(driver);
    sum = driver.addTwo(clerk);

(4) Also recommend declaring addTwo() const and using member-initialization in the ctor

[ZeroesAndOnes]

1. Please initialize variables like total and sum upon declaration, otherwise you have no idea what value's in them before you start using them;

2. In addTwo() the second cout<< should be total, not salary, to give you what you're looking for;

3. The 2 sums you run in main() add (a) salary of driver to that to clerk and (b) salary of clerk to that of itself - are you sure that's what you want or should it be:

    sum = clerk.addTwo(driver);
    sum = driver.addTwo(clerk);

(4) Also recommend declaring addTwo() const and using member-initialization in the ctor

That is an example from a book, but thank you.

I wanted to know at line 31 when I call the function add two and pass the object to the function, in the function add Two, object Employee emp has the same values as the passed object and therefore emp.salary equals 650?
What about the 'salary' variable, what determines which value it has since we are adding them at the line 22.

[sean_cantab]

The salary variable corresponds to the object calling the method, so for e.g in

 sum = clerk.addTwo(driver)

;

object clerk calls the method addTwo() and so salary correspond's to clerk's salary and object driver plays the role of employee emp in this code segment

[ZeroesAndOnes]

The salary variable corresponds to the object calling the method, so for e.g in

 sum = clerk.addTwo(driver)

;

object clerk calls the method addTwo() and so salary correspond's to clerk's salary and object driver plays the role of employee emp in this code segment

That makes sense now, I wasn't paying attention that actually clerk object calls the function addTwo().
If I overloaded + operator, and for example I had situation variable = objectA + objectB , which of there 2 objects would call the method, A or B?

[Elysia]

variable = objectA + objectB is equivalent to

variable = operator+(objectA, objectB)

where operator+ is actually the name of a function.
In case there's no global operator+, the function is always invoked on left-hand-side:

variable = objectA.operator+(objectB)

[ZeroesAndOnes]

variable = objectA + objectB is equivalent to

variable = operator+(objectA, objectB)

where operator+ is actually the name of a function.
In case there's no global operator+, the function is always invoked on left-hand-side:

variable = objectA.operator+(objectB)

Okay, thank you.