Free Test Abstract classes and p... – C++ Lan...

Q1: What is an abstract class in C++?

A. A class that contains at least one pure virtual function B. A class with only concrete functions C. A class without any member functions D. A class that cannot be instantiated but has no pure virtual functions

Q2: How do you declare a pure virtual function?

A. virtual void func() = 0; B. void func() = 1; C. virtual void func() {} D. void func() virtual;

Q3: Can you create an object of an abstract class?

A. No, it is not allowed B. Yes, directly C. Only through pointers D. Only in derived classes

Q4: What must a derived class do if it inherits from an abstract class?

A. Override all pure virtual functions B. Declare itself abstract C. Ignore the pure virtual functions D. Delete the base class

Q5: What happens if a derived class does not override all pure virtual functions?

A. It becomes abstract as well B. It becomes concrete C. It causes a runtime error D. It automatically overrides functions

Q6: Can an abstract class have constructors?

A. Yes, it can B. No, it cannot C. Only default constructor D. Only virtual constructors

Q7: Can abstract classes have non-pure virtual functions?

A. Yes, they can have both B. No, only pure virtual C. Only static functions D. Only inline functions

Q8: Is it possible to define a body for a pure virtual function?

A. Yes, it can have a body B. No, it cannot C. Only in derived classes D. Only if marked virtual twice

Q9: What is the role of an abstract class?

A. To provide an interface and partial implementation B. To hold data only C. To provide a complete implementation D. To replace all base classes

Q10: Can abstract classes be used as base classes?

A. Yes, they are intended for inheritance B. No, they are final C. Only if derived class is abstract D. Only in templates

Q11: Which of these is true about abstract classes?

A. They cannot be instantiated B. They can be copied C. They can be used for variable declarations D. They can be static classes

Q12: What keyword is used to declare a pure virtual function?

A. virtual B. override C. abstract D. final

Q13: What will happen if a class has no pure virtual functions?

A. It is not abstract B. It is abstract C. It cannot be instantiated D. It must be inherited

Q14: Can a class have multiple pure virtual functions?

A. Yes, any number B. No, only one allowed C. Only two D. Only if final

Q15: How does an abstract class differ from an interface in C++?

A. Abstract classes can have data members and function implementations; interfaces have only pure virtual functions B. They are the same C. Interfaces can have data members D. Abstract classes cannot have constructors

Q16: What is a common use case of abstract classes?

A. To define common behavior and force derived classes to implement specifics B. To store static data C. To prevent inheritance D. To encapsulate data

Q17: If a derived class overrides a pure virtual function, what is the effect?

A. Derived class becomes concrete B. Derived class remains abstract C. Derived class cannot be instantiated D. Compiler error

Q18: Can an abstract class be instantiated via a pointer or reference?

A. Yes, to support polymorphism B. No, never C. Only pointers, not references D. Only with casts

Q19: What is required to instantiate a concrete class derived from an abstract class?

A. All pure virtual functions must be implemented B. Base class must be abstract C. No virtual functions in derived D. Derived class must be final

Quiz for Abstract classes and pure virtual functions