Repeating virtual keyword
Hi!
Thanks for all the great help you give here!
My question is if I make a class which inherits from an abstract class
some function
class example
virtual void function() =0;
then it seems to compile whether I have:
class example_one : public example
virtual void function() ={...};
or
class example_two : public example
void function(){....};
so is there a difference/need to repeat the virtual keyword in derived classes?
Hopefully this still made sense without me adding all my confusing code :)
Thanks for all the great help you give here!
My question is if I make a class which inherits from an abstract class
some function
class example
virtual void function() =0;
then it seems to compile whether I have:
class example_one : public example
virtual void function() ={...};
or
class example_two : public example
void function(){....};
so is there a difference/need to repeat the virtual keyword in derived classes?
Hopefully this still made sense without me adding all my confusing code :)
Hi Swizzler,
There is no need to use the virtual keyword in derived classes for pure virtual functions, in fact my compiler complains when I did it.
Cheers TheIdeasMans
There is no need to use the virtual keyword in derived classes for pure virtual functions, in fact my compiler complains when I did it.
Cheers TheIdeasMans
thats quite alright, not quite sure why I am still up at 5am Sunday !!
TheIdeasMan
TheIdeasMan
@ Swizzler: do you know what the virtual keyword does in the first place?
It lets the compiler know it needs to create a virtual table for the function(s) you mark. This has to do with polymorphism -- the ability to use a common base class as if it was any of its derived classes -- which is an abstraction meant to help you design your program.
So you only need to use virtual when you need it. In your case, by adding it, your
http://en.wikipedia.org/wiki/Virtual_function
It lets the compiler know it needs to create a virtual table for the function(s) you mark. This has to do with polymorphism -- the ability to use a common base class as if it was any of its derived classes -- which is an abstraction meant to help you design your program.
So you only need to use virtual when you need it. In your case, by adding it, your
example_one class has a virtual table that you don't need.http://en.wikipedia.org/wiki/Virtual_function
Both ways should compile and give the same result. If the function is virtual in the base class it is automatically virtual in the derived classes.
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