copy constructor

I am having trouble understanding 2 things.

1. the difference between a copy constructor and an operator=
What the actual use of the copy constructor is. I think I get the
operator=

2. do we actually call the operator= or is it called whenever it is
required?

The copy constructor, like all constructors, is only called once in an object's lifetime. Even when you do something like this,

type a = b; // looks like assignment, but isn't

It's the same as

type a(b); // it's actually a copy constructor call

However, if you want to change the state of an object to another object AFTER it has been created, that is when you use the operator =.

Code:

type a(2);  // type(int) constructor
type c(a);  // type(const type&) [copy constructor]
type b;     // type() [default constructor]
b = a;       // operator = (type, type)

All calls to the = operator are explicit, but not everything that looks like it's using the = operator actually does.

the copy constructor is also called when an object is passed-by-value to a function and when a function returns an object