InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
Write a program in C++ to found out whether a word is palindrome or not? |
|
Answer» We cant make a class constructor virtual in C++ to create polymorphic objects. C++ being static typed (the purpose of RTTI is different) language, it is meaningless to the C++ compiler to create an object polymorphically. The compiler must be aware of the class type to create the object. In other words, what type of object to be created is a compile time decision from C++ compiler perspective. If we make constructor virtual, compiler flags an error. In fact except INLINE, no other keyword is allowed in the declaration of constructor. Deleting a derived class object using a pointer to a base class that has a non-virtual destructor results in undefined behavior. To correct this situation, the base class should be defined with a virtual destructor. For example, following program results in undefined behavior. // CPP program WITHOUT virtual destructor // causing undefined behavior #include<iostream> using namespace std; class base { PUBLIC: base() { cout<<"Constructing base \n"; } ~base() { cout<<"Destructing base \n"; } }; class derived: public base { public: derived() { cout<<"Constructing derived \n"; } ~derived() { cout<<"Destructing derived \n"; } }; int MAIN(VOID) { derived *d = new derived(); base *b = d; delete b; getchar(); return 0; } |
|