Question

Can anyone explain this?

1.

Suppose the following function is in the application program that uses the Coord class (Coord_app.cpp):

int print_x(int x)

{



return x;





}

And we want to be able to do the following in main:



int main()

{

Coord C1(5, 8);

cout << get_x(C1) << endl;

}

The idea is that the function get_x expects an integer to be passed to it, but if a Coord object is passed to the function it will be converted to an integer. In this case get_x is passed the Coord object C1(5, 8), which is converted to the integer 5. So the output of the program would be:

5

What prototype specifically would need to be included in Coord.h to make this work?
A-) explicit Coord(int = 0, int = 0);
B-) Coord(int = 0, int = 0);
C-) explicit operator int();
D-) operator int(); correct answer

===================================

2.

In the 2D array project, which of the options below contains a valid call to the overloaded () operator?

array_2D arr1;
A-) operator()(arr1, 5, 7);
B-) arr1.operator()(5, 7); correct
C-) operator()(arr1)(5)(7);
D-) arr1.operator()(5)(7);

=====================================================

3.

In an inheritance relationship:

A base class can have a pure virtual constructor.
A derived class can have a virtual constructor.


A-)
1.. True
2.. True


B-)
1.. False
2.. False correct answer


C-)
1.. True
2.. False


D-)
1.. False
2.. True

Answer 1

Please find the explanations below:

1)
Given code::

int main()

{

Coord C1(5, 8);

cout << get_x(C1) << endl;

}

Here as mentioned get_x expected parameter to be interger. SO if trying to do get_x(C1) will cause run time error.
But it can be resolved by overloading int() operator for the class. Once overloaded than calling class object will
return the value int.
Hence operator int(); required to be in class header file.

2)
To overload parenthesis following is the code..

return type Class::operator()(int row, int col)
Hence arr1.operator()(5, 7); is correct answer.

3)Virtual function works based on virtual table . Virtual table of a class created when constructor of that class called. But if constructor itself is virtual than there will be no any virtual table where it can assign memory. Hence even base or drive class

constructors cannot be virtual