Test Series - cpp

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Test Number 43/102

Q: Which class is used to design the base class?
A. abstract class
B. derived class
C. base class
D. derived & base class
Solution: Abstract class is used to design base class because functions of abstract class can be overridden in derived class hence derived class from same base class can have common method with different implementation, hence forcing encapsulation.
Q: Which is used to create a pure virtual function?
A. $
B. =0
C. &
D. !
Solution: For making a method as pure virtual function, We have to append ‘=0’ to the class or method.
Q: Which is also called as abstract class?
A. virtual function
B. pure virtual function
C. derived class
D. base class
Solution: Classes that contain at least one pure virtual function are called as abstract base classes.
Q: What is meant by pure virtual function?
A. Function which does not have definition of its own
B. Function which does have definition of its own
C. Function which does not have any return type
D. Function which does not have any return type & own definition
Solution: As the name itself implies, it have to depend on other class only.
Q: Pick out the correct option.
A. We cannot make an instance of an abstract base class
B. We can make an instance of an abstract base class
C. We can make an instance of an abstract super class
D. We can make an instance of an abstract derived class
Solution: We cannot make an instance of an abstract base class.
Q: Where does the abstract class is used?
A. base class only
B. derived class
C. both derived & base class
D. virtual class
Solution: As base class only as it helps in encapsulation of similar functioning of derived classes.
Q: What is an abstract class in C++?
A. Class specifically used as a base class with atleast one virtual functions
B. Class specifically used as a base class with atleast one pure virtual functions
C. Class from which any class is derived
D. Any Class in C++ is an abstract class
Solution: An abstract class is defined as a class which is specifically used as a base class. An abstract class should have atleast one pure virtual function.
Q: What is a pure virtual function in C++?
A. A virtual function defined in a base class
B. A virtual function declared in a base class
C. Any function in a class
D. A function without definition in a base class
Solution: Pure virtual function is a virtual function which has no definition/implementation in the base class.
Q: Which is the correct syntax of defining a pure virtual function?
A. pure virtual return_type func();
B. virtual return_type func() pure;
C. virtual return_type func() = 0;
D. virtual return_type func();
Solution: virtual return_type function_name(parameters) = 0; where {=0} is called pure specifier.
Q: Which is the correct statement about pure virtual functions?
A. They should be defined inside a base class
B. Pure keyword should be used to declare a pure virtual function
C. Pure virtual function is implemented in derived classes
D. Pure virtual function cannot implemented in derived classes
Solution: A pure virtual function does not have a definition corresponding to base class. All derived class may or may not have an implementation of a pure virtual function. there is no pure keyword in C++.

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