What is object slicing?

c++ inheritance c++-faq object-slicing
Frankomania picture Frankomania · Nov 8, 2008 · Viewed 190.5k times · Source

Someone mentioned it in the IRC as the slicing problem.

Answer

David Dibben picture David Dibben · Nov 8, 2008

"Slicing" is where you assign an object of a derived class to an instance of a base class, thereby losing part of the information - some of it is "sliced" away.

For example, 

class A {
   int foo;
};

class B : public A {
   int bar;
};

So an object of type B has two data members, foo and bar.

Then if you were to write this:

B b;

A a = b;

Then the information in b about member bar is lost in a.

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