I have two pointers to class A declared globally
A* a; A* b; int main(){ a = new A(...); } How should I invoke a copy constructor to make b as copy BY VALUE of a. class A does not have any pointers as fields.
I do have a constructor declared, but I can remove it in order to not override the default one.
Thanks
There are two things wrong with your code, that need to be fixed before answering the question.
unique_ptr or just plain object (unless the object is supposed to live longer than main(), but that's a weird case).So, after correcting the code, it looks like this:
int main() { A a; A b(a); } If you need to access those objects from other parts of the code, without explicitly passing them around, put them in sensibly named namespace:
// in header namespace a_and_b // this is *wrong* name for it, of course { extern A a; extern A b; } // in one of TUs - also possible to wrap this in namespace ... { ... } A a_and_b::a; A a_and_b::b(a_and_b::a); Of course, if you are just asking for syntax, the answer would be:
A * b = new A(*a); so just dereference the pointer to get A out of A *. But please, don't ever do this - even in freestanding environment you can easily implement own smart pointer to wrap this in sane way.
Simply call the copy constructor with new:
b = new A(*a); I gotta ask though... why not keep two static objects instead?
If you don't declare one you always get an implicit constructor, copy constructor and destructor that you can call like StoryTeller said;
b = new A(*a); If you want to do anything in the copy constructor you need to write one, here's a bit about how you do that: http://www.cplusplus.com/articles/y8hv0pDG/
