August
1997 QUESTION 3 Total Marks: 20 Marks |
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| 3. | (a) Polymorphism is an important characteristic of object-oriented programming; it can be defined in C++ using virtual functions. Define a virtual function example that takes an integer parameter and returns void. | [3] | |
| (b) The use of virtual functions allows dynamic binding. Explain what is meant by dynamic binding and explain how it is different from static binding. | [4] | ||
| (c) State one advantage and one disadvantage of dynamic binding. | [2] | ||
| (d) What is a friend function? | [2] | ||
| (e) In the context of friend functions, give a reasoned answer to the following questions. | |||
| (i) if Dog class is a friend of Boy class, is Boy a friend of Dog? | [3] | ||
| (ii) if Dog is a friend of Boy, and Terrier derives from Dog, is Terrier a friend of Boy? | [3] | ||
| (iii) if Dog is a friend of Boy, and Boy is a friend of House, is Dog a friend of House? | [3] | ||