How to construct virtual constructor
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Answer / richa
Constructors can't be virtual in C++.It is an error.The
destructors on the other hand can be virtual.
| Is This Answer Correct ? | 29 Yes | 4 No |
Answer / shakti singh khinchi
Virtual constructors are not used in any case in c++, bcz
the construction order in c++ should always remains from
base to derived , no one can changed their construction
order, so no need to declare constructor as virtual. But if
anyone wants to make it virtual then it is possible to make
a constructor virtual but it is against the OOPs.
| Is This Answer Correct ? | 12 Yes | 2 No |
Answer / mmszubeir
C++ doesn’t give any direct support to declare a virtual
constructor as such. But we can have a virtual constructor
by indirectly providing the mechanism.
As like ordinary virtual functions, a virtual constructor
can exhibit different behaviors depending upon the request.
That is, a virtual constructor can construct different
types of objects on different requests. This implies the
class hierarchy should be polymorphical.
This technique resembles two stage construction technique.
To avoid breaking at the constructor of an object, we keep
the heavy initialization code in a separate initializer
function so that we get the minimum guarantee that the
constructor won’t fail.
In this case, we first invoke the constructor and then
invoke the initializer function. The advantage of this
method is that we will have a better control of the
construction.
For example,
CBrush blueBrush; // Just an object. Must be initialized!
blueBrush.CreateSolidBrush(RGB(0,0,255)); // Blue brush.
Since I am running short of time, I hang on with this for
the time being. I will add more details about the virtual
constructor theory soon.
| Is This Answer Correct ? | 10 Yes | 5 No |
Answer / nishant
Firstly Virtual constructor is really not needed at all.
Explanation:
V-table is something which stores the addresses corrospond
to all virtual function within a class.Now every class
object contains virtual pointer points to base address of
v-table in memory which is being used to resolve the
corrosponding virtual function addresses.
This v-table construction is done when object of the class
has been created,While constructor is an initialization
process in construction of the object and so v-table is not
available during initialization process and hence virtual
constructor is not possible.
| Is This Answer Correct ? | 4 Yes | 0 No |
Answer / vishwa
there is no need to use vitual constructors in C++.
because the construction of the class tree will be happened
from the base class to child class.
| Is This Answer Correct ? | 9 Yes | 9 No |
Answer / gaurav
The first thing, Why we need a Virtual constructors, do we
really need that..... :) If I am making an object of A then
I should not expect the object of class B as I can directly
make a B class object.
| Is This Answer Correct ? | 1 Yes | 4 No |
What is the output of the following 3D Array int arr[3][2][2]={1,2,3,4,5,6,7,8,9,10,11,12}; what is the output for arr[2][1][0]?
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STL 
