Copy Assignment Operator

Is when you make one object equal to another. Both already exists. Remember to always check for self assignment to make it correct.

class Test {
public:
    Test() {};
    Test(const Test& t) {
        cout << "Copy constructor called " << endl;
    };
    Test& operator=(const Test& t) {
        cout << "Assignment operator called " << endl;
        return *this;
    };
};

Copy Constructor vs. Copy Assignment Operator

The fields are already initialized. Therefore, we need to do some cleanup. On the other hand, in case of a Copy Constructor, fields are not initialized. So we don’t worry about cleanup.

A a;
A c;
A b = a; // Calls copy constructor
a = c; // Calls copy assignment constructor, since both objects are initialized already

Strategies for Implementation

Method 1: (the one I will be using?)

1. check for self assignment: if(this != &other)
2. delete the old resource: delete this->next
3. allocate new resource this->next = new Object{ *other.next } #4 return *this

Method 2

1. Allocate temporary object on STACK: Obj temp(rhs)
2. SWAP the internal data with “this”: swap(temp.pointer, this→pointer)
3. return *this (destructor will clean up the old resources, which got swapped into temp object)