Why is copy constructor not allowed pass by value? [duplicate]

Answer 1

Passing by value (rather than by reference) means a copy needs to be made. So passing by value into your copy constructor means you need to make a copy before the copy constructor is invoked, but to make a copy you first need to call the copy constructor.

Answer 2

Passing by value means that the parameter is copied into the function. That calls the copy constructor.

If your copy constructor parameter is pass-by-value... It would call itself... over and over again...

Answer 3

When a function is passed with a parameter, local variable is created corresponding to the parameter and is copied with the argument passed on to the function invocation. Hence when the function is invoked, copy constructor of the function will be invoked to copy the argument passed to the invocation to the local variable created. This results in a endless loop.

Where as when a reference is passed on to the function , local variable is not created corresponding to the parameter.