C++ Copying vs Assignment Copy Constructor
Example
Copy constructor on the other hand , is the complete opposite of the Assignment Constructor. This time, it is used to initialize an already nonexistent(or non-previously initialized) object. This means it copies all the data from the object you are assigning it to , without actually initializing the object that is being copied onto. Now Let's take a look at the same code as before but modify the assignment constructor to be a copy constructor :
// Copy Constructor
#include <iostream>
#include <string>
using std::cout;
using std::endl;
class Foo
{
public:
Foo(int data)
{
this->data = data;
}
~Foo(){};
Foo(const Foo& rhs)
{
data = rhs.data;
}
int data;
};
int main()
{
Foo foo(2); //Foo(int data) called
Foo foo2 = foo; // Copy Constructor called
cout << foo2.data << endl;
}
You can see here Foo foo2 = foo; in the main function I immediately assign the object before actually initializing it, which as said before means it's a copy constructor. And notice that I didn't need to pass the parameter int for the foo2 object since I automatically pulled the previous data from the object foo. Here is an example output : http://cpp.sh/5iu7
