Copy constructor and assignment operator invoked at same time

[NovaPrimeveera]

Dear C++ Community

I found an interesting question in my test about describing a circumstance in which a copy constructor and an assignment operator for a class would be invoked. I did not understand this question after researching it.

[mbozzi]

I am right in assume they want a real-life example?

As real-life as a contrived example can be, copy-and-swap comes to mind:

#include <iostream>
#include <utility>

struct X
{
  explicit X(int n)
    : pn(new int{n}) {} 
  
  ~ X() { delete pn; } 

  X(X const& other)
    : pn(new int {other.get()}) {}

  X& operator=(X lhs)
  { 
    using std::swap;
    swap(lhs.pn, pn); 
    return *this;
  } 
  
  int get() const { return *pn; }
private:
  int* pn = nullptr;
};

int main() 
{ 
  X x{2}, y{4}; 
  // conventionally, y is copied into the parameter of the operator=
  x = y; 

  std::cout << x.get() << ' ' << y.get() << '\n';
} 

http://coliru.stacked-crooked.com/a/a9ce856c1dbbf2aa