Question

I wonder if there is something wrong with the copy constructor function below?

class A
{
   private:
      int m;
   public:
      A(A a){m=a.m}
}

Answer 1

Two things:

• Copy constructors must take references as parameters, otherwise they are infinitely recursive (in fact the language won’t allow you to declare such constructors)

• It doesn’t do anything the default copy ctor doesn’t do, but does it badly – you should use initialisation lists in a copy ctor wherever possible. And if the default copy ctor does what you want, don’t be tempted to write a version yourself – you will probably only get it wrong, and you will need to maintain it.