What does slicing mean in C++?

Question

It is mentioned in C++ FAQ site -- \"larger derived class objects get sliced when passed by value as a base class object\", what does slicing mean? Any sample to demonstrate

Answer 1

Slicing is basically removing the derivedness of the derived class object to behave as if it were a base class object.

For ex:

class A
{
public:
   int x;
};

class B : public A
{
public:
   int y;
};

void test(A a)
{
}

int main()
{
 B b;
test(b); // here the object b will be visible as A object in method test
//none of the B's data or methods are available.
}