If they both match the same, but are different functions, an ambiguity error results.
However for class types, identity assignment is not allowed.
However, it is invoked implicitly when something is done that causes a COPY of an existing object to be created.
This happens when: Since the purpose of a copy constructor is to not only initialize the data in an object, but to initialize it as a copy of another existing object, the original object must be passed in as a parameter.
These functions include: The automatic versions of the constructor and destructor don't do anything, but they will be there if you do not build them.
(The constructor you get is the "default constructor" -- no parameters -- and this is automatically built if you don't define any constructor besides the cop constructor).(That’s why some guidelines are written in terms of member pointers, because such pointers often “own” the storage they point to, and if they do, copying will likely have to manage the storage to deallocation and allocation.)Whenever possible, you should make your classes behave like values.For such a class X, that implies, among other things, that the following holds: That means that in addition to making sure that copying works, comparison for equality and inequality should work too.to a function parameter means that the function will not make a copy.Here it means the same thing: when the function returns a value, it will be the actual object we return, not a copy (normally, returning a value does make a copy).This will especially pose problems if, when the copy goes out of scope, it cleans up the dynamic data along with it.When there is a pointer (inside an object) that points to dynamic data, the shallow copy is not sufficient, because it does not copy the dynamic data, only the pointer. Here is what we might write for a copy constructor definition in the Directory class (from the phonebook database example): Like the copy constructor, the assignment operator has to make a copy of an object. If a deep copy is desired for assignments on a user-defined type (e.g.If this object is passed into a function by value, a copy will be made, and the new object's numerator will be 3, denominator 4. Consider, however, the Directory class of the phone book example.The member data variables were currentsize and maxsize (both of type int), and a pointer, entry List (of type Entry * ), which pointed to dynamically allocated data outside the actual object.All class types have reference semantics, so identity assignment by default rebinds the left-hand-side to the argument at the right, and this is not overridable.The code example below shows a simple implementation of a 2-dimensional array with overloaded indexing and slicing operators.