What is Object Slicing and When Does it Occur in Inheritance?

Object Slicing: Losing Data in Inheritance

In object-oriented programming, inheritance allows classes to extend the functionality of their parent classes. However, this inheritance mechanism can introduce a phenomenon known as object slicing, which can result in data loss.

What is Object Slicing?

Object slicing occurs when an object of a derived class is assigned to an instance of a base class. During this assignment, a portion of the derived class's data becomes inaccessible and is "sliced" away.

When Does Object Slicing Occur?

Consider the following two classes:

class A {
   int foo;
};

class B : public A {
   int bar;
};

An instance of class B contains two data members: foo (inherited from A) and bar. However, if you assign an object of type B to an instance of type A as follows:

B b;
A a = b;

The data member bar in the b object becomes inaccessible in the a object, resulting in object slicing. This happens because a is treated as a base class instance, and it has no knowledge of the bar member defined in the derived class B.

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