| When we use enumerations, by default the values assigned to enumerations start from zero. Suppose you have two classes with classA and classB with enumeraions defined as below. For classA: enum { santro,zen } cars; For classB: enum { Kinetic,sunny} bikes; Now in a function you get some integer which should indicate the type of car or type bike. void findType(int nType) { if( nType == classA::santro ) { cout< } if( nType == classA::zen) { cout< } if( nType == classB::kinetic) { cout< } if( nType == classB::sunny) { cout< } } Now with such a code you will always find out put as santro kinetic OR zen sunny This is because though while coding we use classA::santro and classB::kinetic, both the variables have the same value i.e. zero. Thus for any value of nType (0 or 1 ), always two if conditions are satisfied, giving the wrong result . So if you are using two enumeraions in a single function you should always make sure to avoid the clash between them. For this we can use the following code to add the offset to one of the enumeraions. enum { kinetic = 100, sunny } bikes; Thus values of the enums bikes and cars, will differ in value and the clashing between the two will be avoided.( You also have to adjust the values of the variable nType passed to the function accordingly.) If two enumeraions are being used in same function, then care should be taken to avoid the clashing between the two. |
Polymorphism is the ability of different objects to react in an individual manner to the same message. This notion was imported from natural languages. For example, the verb "to close" means different things when applied to different objects. Closing a door, closing a bank account, or closing a program's window are all different actions; their exact meaning is determined by the object on which the action is performed. Most object-oriented languages implement polymorphism only in the form of virtual functions. But C++ has two more mechanisms of static (meaning: compile-time) polymorphism: Operator overloading. Applying the += operator to integers or string objects, for example, is interpreted by each of these objects in an individual manner. Obviously, the underlying implementation of += differs in every type. Yet, intuitively, we can predict what results are. Templates. A vector of integers, for example, reacts differently from a vector of string objects when it receives ...
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