Programmers seem to hate coding something from scratch; why code the same thing over and over again? Fortunately, it is possible to reuse code, thanks to one of the key concepts of object-oriented programming. That is inheritance, which is the subject of this article. So if you're looking for a clear explanation of how inheritance works in C++, keep reading.
Inheritance in C++ - Inheritance in General (Page 3 of 5 )
These are key concepts in object-oriented programming. In addition, you should note that no constructors, deconstructors, or base class operators will be inherited, as these are too specific to work generally on the hierarchy tree constructed by an inheritance. Look over the iostream hierarchy tree shown below.
This sums up the possibilities of inheritance inside C++ very well. The ios is the base class that holds common tasks for an input and output stream of data. These include details like where to store the data and how it is managed inside the stream.
The istream and ostream are specifications of the ios and are considered derived classes from the ios base class. As you may conclude, multiple inheritance is also possible, and you can individually set their access inheritance specifies. For example, you can set one public and the other protected (remember this is only for example purposes; this is implemented differently in the iostream library):
class iostream: public istream, protected ostream
The method is to split them with a comma and specify for each of them what type of inheritance to execute. Remember that if you leave this empty, it's private inheritance by default. Multiple inheritances should be used carefully and only by experienced programmers, as they tend to be a little more complicated to maintain and code correctly.
The iostream class is the direct derived class of both the istream and ostream classes. If you climb up further in the hierarchy tree, the ios class is the indirect base of the iostream class.