Why pass by reference for copy constructor?

#1

I was unable to understand this part, it was confusing.

#2

hello @S_yajur

A copy constructor is called when an object is passed by value. Copy constructor itself is a function. So if we pass an argument by value in a copy constructor, a call to copy constructor would be made to call copy constructor which becomes a non-terminating chain of calls. Therefore compiler doesn’t allow parameters to be passed by value.

#3

I am unable to understand, why is there a non-terminating chain of calls?
Can u please explain in reference to this example:

class car
{
Car(Car x) // call by value
{
//body
}
}

main()
{
Car d;

Car d(e);   // calling copy constructor

}

#4

here e will be passed as a parameter to this ->

copy constructor right?

#5

yes sir, that is a copy constructor. but i still dont get it

#6

so that means first
e will be copied to x right?

#7

If u passed by value to copy constructer,it will call itself,to copy the actual parameter to formal parameter,it will call a endless chain of call to copy constucter,this process would go on untill the system runs out of memory

#8

So you are saying for copying from e to x, again copy constructor would be called, but i thought copy constructor is invoked by
Car e(x); or Car x=e;

without these statements how it is calling the copy constructor again?

#9

when e will be passed to copy constructor then first e will be copied to x.
and for copying e to x again copy constructor will be called.
and this will happen again n again

1 Like
#10

so is it like when e is copying to x (for 1st time out of n times), it will call copy constructor bcos of which compiler will try to copy e to x(for 2nd time) and call copy constr and again compiler will try to copy e to x(for 3rd time)…and it goes on for n times.

Am i correct sir?

#11

yeah …

#12

Thank you sir for explaining

#13

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