Virtual Function Table

Every now and then you read in books or magasins that C++ gets slow when virtual functions are used, because it must be determined at run-time which function must be executed.
Well, I wrote a set of classes and a test program to measure the performance of the following different implementations:

• Class without any virtual function.
• Class with a virtual destructor.
• Class where the function that's called is defined virtual.
• Class with a virtual destructor and the function defined as virtual.
• Class derived from a base class (interface-like) which defined the function as pure virtual, and the implementation in the derived class.

Since the test function itself didn't do much I had to call it several million times to get a run-time in seconds for every test. And the result was: No difference at all, every type of implementation showed the same run-time behaviour, the difference between the different measured times was less than 1 percent.

So, use base classes and virtual functions and all the fancy features that C++ offers!