Paper - II (v) — Object Oriented Programming using C++ and JAVA MCQ — 45 Practice Questions with Answers

Explanation

Java distinguishes checked exceptions from unchecked exceptions. A method that may throw a checked exception must either handle it using an appropriate catch clause or declare it using a throws clause so the obligation is visible to callers. This rule is especially relevant in file handling, where input-output operations commonly declare checked exceptions.

Explanation

The C++ stream library separates common file-stream roles: ifstream for input, ofstream for output, and fstream for file streams that can support both input and output depending on the open mode. A stringstream is also a stream, but it uses an in-memory string buffer rather than a file.

Explanation

C++ run-time polymorphism through a base pointer or reference depends on virtual functions. If the base class declares a member function virtual and the derived class provides a matching override, the call is dispatched according to the dynamic type of the object. Changing storage duration, data-member access, or overload sets does not create dynamic binding.

Explanation

A pure virtual function expresses an abstract operation in a C++ class. The class cannot be directly instantiated, and a derived class that is meant to be concrete must provide final implementations for all inherited pure virtual functions. This is a core way to model interface-like behavior in C++ without changing access rules or involving Java interfaces.

Explanation

Encapsulation keeps an object's internal representation behind a public interface. For a field such as balance, the class should retain private storage and expose operations such as deposit or withdraw that validate amounts before changing the state. This is different from simply hiding data for its own sake; the point is to protect class invariants while still allowing useful operations.