Learning to Program in C++

For the Benefit of Posterity

Now it's time to clear up a point we've glossed over so far. We have already seen that the member initialization expression m_Count(0), present in the constructors for the StockItem object, is there just to make sure we don't have an uninitialized variable in the StockItem object—even though we won't be using m_Count in a StockItem object. While this is true as far as it goes, it doesn't answer the question of why we need this variable at all if we're not using it in the StockItem class. The clue to the answer is that we are using that member variable in the object pointed to by m_Worker (i.e., m_Worker->m_Count). But why don't we just add the m_Count variable when we create the UndatedStockItem class rather than ...