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What are Virtual Functions? How to implement virtual
functions in "C" ?
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Answer / arati pradhan
A function declared with the keyword virtual, termed as
virtual function.It is used for runtime polymorphism. When
a function is declared as virtual function, the function of
that object is invoked which is refernced by the base
pointer.
Example-
class BASE
{
public:
virtual void show()
{
cout<<"withen base";
}
};
class DERIVED:public BASE
{
public:
void show()
{
cout<<"withen derived";
}
};
void main()
{
BASE *b,b1;
DERIVED d1;
b=&b1;
b->show(); //call the BASE show()
b=&d1;
b->show(); //call the DERIVED show()
getch();
}
| Is This Answer Correct ? | 9 Yes | 4 No |
Answer / jaroosh
To address the second part of the question - the only way to
implement mechanism like virtual functions in C is by using
function pointers, creating structure emulating Virtual
Pointer Table etc.
Implementation is rather complicated and creates a lot of
overhead for every structure that we want to use with
virtual functions (since ANSI C doesnt support inheritance
and polimorphism, it also calls for emulating this behavior,
so virtual functions for C is actually more of a form of art
than anything usefull).
| Is This Answer Correct ? | 7 Yes | 2 No |
Answer / rama
When we use the same function name in both the base and the
derived classes, the function in base class is declared as virtual...we must access virtual function through the use of a pointer declared as a pointer to the base class..
In other words, virtual function is defined in the base class,it need not be necessarily redefined in the derived class. In such cases,the respective calls will invoke the base class function.
| Is This Answer Correct ? | 2 Yes | 0 No |
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