Differentiate between a deep copy and a shallow copy?
Deep copy involves using the contents of one object to create
another instance of the same class. In a deep copy, the two objects may
contain ht same information but the target object will have its own
buffers and resources. the destruction of either object will not affect the
remaining object. The overloaded assignment operator would create a
deep copy of objects.
Shallow copy involves copying the contents of one object into
another instance of the same class thus creating a mirror image. Owing
to straight copying of references and pointers, the two objects will share
the same externally contained contents of the other object to be
Using a copy constructor we simply copy the data values member by member. This method of copying is called shallow copy. If the object is a simple class, comprised of built in types and no pointers this would be acceptable. This function would use the values and the objects and its behavior would not be altered with a shallow copy, only the addresses of pointers that are members are copied and not the value the address is pointing to. The data values of the object would then be inadvertently altered by the function. When the function goes out of scope, the copy of the object with all its data is popped off the stack.
If the object has any pointers a deep copy needs to be executed. With the deep copy of an object, memory is allocated for the object in free store and the elements pointed to are copied. A deep copy is used for objects that are returned from a function