Is it possible to have Virtual Constructor? If yes, how?If not, Why not possible ?
There is nothing like Virtual Constructor.
The Constructor cant be virtual as the constructor is a code which is responsible for creating a instance of a class and it cant be delegated to any other object by virtual keyword means.
What about Virtual Destructor?
Yes there is a Virtual Destructor. A destructor can be virtual as it is possible as at runtime depending on the type of object baller is balling to , proper destructor will be called.
What is Pure Virtual Function? Why and when it is used ?
The abstract class whose pure virtual method has to be implemented by all the classes which derive on these. Otherwise it would result in a compilation error.
This construct should be used when one wants to ensure that all the derived classes implement the method defined as pure virtual in base class.
What is problem with Runtime type identification?
The run time type identification comes at a cost of performance penalty. Compiler maintains the class.
How Virtual functions call up is maintained?
Through Look up tables added by the compile to every class image. This also leads to performance penalty.
Can inline functions have a recursion?
Syntax wise It is allowed. But then the function is no longer Inline. As the compiler will never know how deep the recursion is at compilation time.
How do you link a C++ program to C functions?
By using the extern “C” linkage specification around the C function declarations.
Programmers should know about mangled function names and type-safe linkages. Then they should explain how the extern “C” linkage specification statement turns that feature off during compilation so that the linker properly links function calls to C functions.
Explain the scope resolution operator?
It permits a program to reference an identifier in the global scope that has been hidden by another identifier with the same name in the local scope.
How many ways are there to initialize an int with a constant?
1. int foo = 123;
2. int bar(123);