What is the difference between overriding overloading and shadowing as well as hiding while using inheritance?

Answer 1

Overloading has nothing to do with inheritance. Overloading is simply a means by which you can provide two or more different ways to call the same function, according to the number and type of arguments you pass to the function.

Overriding is where a derived method provides a new implementation for a base class method. The override may augment the base class method simply by calling the base class method at any time, thus the new implementation need only cater for any differences between the two implementations.

Hiding occurs when you override a base class method that is also overloaded. All the base class overloads are effectively hidden by the overridden method, making them unavailable to the derived class. You must override each overload in order to make it visible to the derived class.

Ideally, you should only override methods that are declared virtual in the base class. In this way you gain the benefits of polymorphic behaviour: when you implicitly call a base class method, the override will be executed instead, thus ensuring all derived objects exhibit correct behaviour, even without prior knowledge as to what those derivatives may be.

Shadowing is similar to hiding insofar as the override "masks" the base class method. However, shadowing is more concerned with nested code blocks that declare the same variable name within the same namespace, and therefore has nothing whatsoever to do with inheritance. For instance, in the following example, the integer i in the outer code block is shadowed by the integer i in the inner code block. What this means is that the value of i in the outer block is not accessible to the inner block, because the i in the inner block masks it. Although this behaviour can sometimes be desirable, it is best avoided as it can lead to ambiguity about which instance of i you are actually referring to, and makes your code that much harder to follow.

for(int i=0; i<3; ++i )

{

std::cout<<i<<std::endl;

for(int i=0; i<3; ++i)

{

std::cout<<i<<" ";

}

std::cout<<std::endl;

}

Output:

0

0 1 2

1

0 1 2

2

0 1 2