Predict the output of following program?
Size of an empty class is not zero. It is 1 byte generally. It is nonzero to ensure that the two different objects will have different addresses. See the following example.
For the same reason (different objects should have different addresses), “new” always returns pointers to distinct objects. See the following example.
Now guess the output of following program (This is tricky)
Note that the output is not greater than 4. There is an interesting rule that says that an empty base class need not be represented by a separate byte. So compilers are free to make optimization in case of empty base classes. As an exercise, try the following program on your compiler.
sizeof(Empty) 1 sizeof(Derived1) 1 sizeof(Derived2) 8 sizeof(Derived3) 1 sizeof(Derived4) 16 sizeof(Dummy) 1
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Improved By : divya_dashrath_barvekar