Copy constructor

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Why should the copy constructor accept its parameter by reference in C++?

Why the argument to a copy constructor is passed by reference?

Exact duplicate of [Why should the copy constructor accept its parameter by reference in C++?](http://stackoverflow.com/questions/2685854/why-should-the-copy-constructor-accept-its-parameter-by-reference-in-c). — James McNellis, Jun 02 '10 at 14:40

score 10 · Answer 1 · answered Jun 02 '10 at 14:33

10

If it is passed by value it would require making a copy using a...COPY CONSTRUCTOR. :-)

answered Jun 02 '10 at 14:33

Amardeep AC9MF

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score 3 · Answer 2 · answered Jun 02 '10 at 14:35

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You can't pass it by value because pass-by-value implies making/passing a copy of the thing ... making a copy of the parameter passed to the copyy constructor would be recursive, cause a stack overflow.

answered Jun 02 '10 at 14:35

ChrisW

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score 1 · Answer 3 · answered Jun 02 '10 at 14:39

As others have mentioned you can't pass it by value - because then you'd need a copy to create a copy!

The only other alternative would be to pass by pointer, but the syntax would require address-of, like so:

MyClass copy(otherclass);  // by reference
MyClass copy(&otherclass); // by pointer

Copy constructor

3 Answers3