C++ Programming Multiple Choice Questions - Inheritance
This section focuses on the "Inheritance" in C++ programming langauge. These Multiple Choice Questions (MCQ) should be practiced to improve the C++ programming skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.
1. When the inheritance is private, the private methods in base class are __________ in the derived class (in C++).
A. Inaccessible
B. Accessible
C. Protected
D. Public
View Answer
Ans : A
Explanation: When the inheritance is private, the private methods in base class are inaccessible in the derived class (in C++).
2. Which design patterns benefit from the multiple inheritances?
A. Adapter and observer pattern
B. Code pattern
C. Glue pattern
D. None of the mentioned
View Answer
Ans : A
Explanation: A template is a formula for creating a generic class
3. What is meant by multiple inheritance?
A. Deriving a base class from derived class
B. Deriving a derived class from base class
C. Deriving a derived class from more than one base class
D. None of the mentioned
View Answer
Ans : C
Explanation: Multiple inheritance enables a derived class to inherit members from more than one parent.
4. What will be the order of execution of base class constructors in the following method of inheritance.class a: public b, public c {...};
A. b(); c(); a();
B. c(); b(); a();
C. a(); b(); c();
D. b(); a(); c();
View Answer
Ans : A
Explanation: b(); c(); a(); the order of execution of base class constructors in the following method of inheritance.class a: public b, public c {...};
5. Inheritance allow in C++ Program?
A. Class Re-usability
B. Creating a hierarchy of classes
C. Extendibility
D. All of the above
View Answer
Ans : D
Explanation: Advantage of inheritance are like re-usability- You can re-use existing class in a new class that avoid re-writing same code and efforts.We can make an application easily extensible.
6. Can we pass parameters to base class constructor though derived class or derived class constructor?
A. Yes
B. No
C. May Be
D. Can't Say
View Answer
Ans : A
Explanation: Yes, we pass parameters to base class constructor though derived class or derived class constructor.
7. What are the things are inherited from the base class?
A. Constructor and its destructor
B. Operator=() members
C. Friends
D. All of the above
View Answer
Ans : D
Explanation: These things can provide necessary information for the base class to make a logical decision.
8. Which of the following advantages we lose by using multiple inheritance?
A. Dynamic binding
B. Polymorphism
C. Both Dynamic binding & Polymorphism
D. None of the mentioned
View Answer
Ans : C
Explanation: The benefit of dynamic binding and polymorphism is that they help making the code easier to extend but by multiple inheritance it makes harder to track.
9. What is the output of this program?
Note:Includes all required header files
using namespace std;
class Base
{
public:
Base(){}
~Base(){}
protected:
private:
};
class Derived:public Base
{
public:
Derived(){}
Derived(){}
private:
protected:
};
int main()
{
cout << "Executed" << endl;
}
A. Executed
B. Error
C. Runtime error
D. None of the mentioned
View Answer
Ans : B
Explanation: We are not allowed to overload the constructors, So it is arising an exception.
10. What is the output of this program?
Note:Includes all required header files
using namespace std;
int main()
{
string s = "a long string";
s.insert(s.size() / 2, " * ");
cout << s << endl;
return 0;
}
A. long* string
B. a long st*ring
C. Depends on compiler
D. None of the mentione
View Answer
Ans : C
Explanation: In this program, We are placing the string based on the size of the string and it is a string hierarchy.
11. What is the output of this program?
Note:Includes all required header files
using namespace std;
struct a
{
int p;
};
struct b
{
int* x;
};
struct c : public a, public b
{
};
int main()
{
c* p = new c;
p->x = 0;
cout << "Inherited";
return 0;
}
A. Inherited
B. Error
C. Runtime error
D. None of the mentioned
View Answer
Ans : A
Explanation: In this program, We apply the multiple inheritance to structure.
12. What is the output of this program?
Note:Includes all required header files
using namespace std;
class Base1 {
public:
Base1()
{ cout << " Base1" << endl; }
};
class Base2 {
public:
Base2()
{ cout << "Base2" << endl; }
};
class Derived: public Base1, public Base2 {
public:
Derived()
{ cout << "Derived" << endl; }
};
int main()
{
Derived d;
return 0;
}
A. Compiler Dependent
B. Base1
Base2
Derived
C. Base2 Base1 Derived
D. Compiler Error
View Answer
Ans : B
Explanation: When a class inherits from multiple classes, constructors of base classes are called in the same order as they are specified in inheritance.
13. Which of the following is true about the following program
Note:Includes all required header files
using namespace std;
class Base1 {
public:
~Base1() { cout << " Base1" << endl; }
};
class Base2 {
public:
~Base2() { cout << " Base2" << endl; }
};
class Derived: public Base1, public Base2 {
public:
~Derived() { cout << " Derived" << endl; }
};
int main()
{
Derived d;
return 0;
}
A. Base1
Base2
Derived
B. Derived
Base2
Base1
C. Derived
D. Compiler Dependent
View Answer
Ans : B
Explanation: Destructors are always called in reverse order of constructors.
14. Assume that an integer takes 2 bytes and there is no alignment in following classes, predict the output.
Note:Includes all required header files
using namespace std;
class base {
int arr[15];
};
class b1: public base { };
class b2: public base { };
class derived: public b1, public b2 {};
int main(void)
{
cout << sizeof(derived);
return 0;
}
A. 30
B. 60
C. 0
D. 120
View Answer
Ans : D
Explanation: Since b1 and b2 both inherit from class base, two copies of class base are there in class derived. This kind of inheritance without virtual causes wastage of space and ambiguities. virtual base classes are used to save space and avoid ambiguities in such cases.
15. What will be the output of this program?
#include <iostream>
using namespace std;
class Base {};
class Derived: public Base {};
int main()
{
Base *p = new Derived;
Derived *q = new Base;
}
A. error: invalid conversion from "Derived*" to "Base*"
B. No Compiler Error
C. error: invalid conversion from "Base*" to "Derived*"
D. Runtime Error
View Answer
Ans : C
Explanation: A Base class pointer/reference can point/refer to a derived class object, but the other way is not possible.
16. What will be the output of the following program?
#include <iostream>
using namespace std;
class Base
{
public:
int lfc() { cout << "Base::lfc() called"; }
int lfc(int i) { cout << "Base::lfc(int i) called"; }
};
class Derived: public Base
{
public:
int lfc() { cout << "Derived::lfc() called"; }
};
int main()
{
Derived d;
d.lfc(5);
return 0;
}
A. Base::lfc(int i) called
B. Derived::lfc() called
C. Base::lfc() called
D. Compiler Error
View Answer
Ans : D
Explanation: If a derived class writes its own method, then all lfc function of base class with same name become hidden, even if signaures of base class lfc function are different. In the above question, when lfc() is rewritten in Derived, it hides both lfc() and lfc(int) of base class.
17. State whether the following statements about inheritance are True or False.
i) A public member of a class can be accessed by its own objects using the dot operator.
ii) While inheriting, the private members of the base class will never become the members of its derived class.
A. True, False
B. False, True
C. True, True
D. False, False
View Answer
Ans : C
Explanation: None.
18. In inheritance, order of execution of base class and derived class destructors are:
A. Base to derived
B. Derived to base
C. Random order
D. None of the above
View Answer
Ans : D
Explanation: In inheritance, execution order of constructors are always from base to derived and destructors call order is in reverse i.e. from derived to base. In polymorphic classes, means the class that contain virtual functions, we need to make destructor virtual in base class. Other wise the derived class destructor will not be called
19. What is the difference between protected and private access specifiers in inheritance?
A. Private member is not inheritable and not accessible in derived class.
B. Protected member is inheritable and also accessible in derived class.
C. Both are inheritable but private is accessible in the derived class.
D. Both are inheritable but protected is not accessible in the derived class.
View Answer
Ans : B
Explanation: Protected member is inheritable and also accessible in derived class is the difference between protected and private access specifiers in inheritance.
20. Which value is placed in the base class?
A. Derived values
B. Default type values
C. Both A & B
D. None of the mentioned
View Answer
Ans : B
Explanation: We can place the default type values in a base class and overriding some of them through derivation.
21. The friend functions and the member functions of a friend class can directly access the______________ data.
A. Private and protected
B. Private and public
C. Protected and public
D. Private, protected and public
View Answer
Ans : A
Explanation: the friend functions and the member functions of a friend class can directly access the Private and protected data
22. What will be the order of execution of base class constructors in the following method of inheritance. class a: public b, virtual public c {...};
A. b(); c(); a();
B. c(); b(); a();
C. a(); b(); c();
D. b(); a(); c();
View Answer
Ans : B
Explanation: c(); b(); a(); will be the order of execution of base class constructors in the following method of inheritance. class a: public b, virtual public c {...};
23. class X, class Y and class Z are derived from class BASE. This is ______ inheritance.
A. Multiple
B. Multilevel
C. Hierarchical
D. Single
View Answer
Ans : C
Explanation: None
24. Reusability of the code can be achieved in CPP through ______ .
A. Polymorphism
B. Encapsulation
C. Inheritance
D. Both A and C
View Answer
Ans : C
Explanation: None
25. What will be the output of the following program?
Note:Includes all required header files
class find {
public:
void print() { cout <<" In find"; }
};
class course : public find {
public:
void print() { cout <<" In course"; }
};
class tech: public course { };
int main(void)
{
tech t;
t.print();
return 0;
}
A. In find
B. In course
C. Compiler Error: Ambiguous call to print()
D. None of the above
View Answer
Ans : B
Explanation: The print findction is not present in class tech. So it is looked up in the inheritance hierarchy. print() is present in both classes find and course, which of them should be called? The idea is, if there is multilevel inheritance, then findction is linearly searched up in the inheritance hierarchy until a matching findction is found.
26. Which symbol is used to create multiple inheritance?
A. Dot
B. Comma
C. Dollar
D. None of the above
View Answer
Ans : B
Explanation: For using multiple inheritance, simply specify each base class (just like in single inheritance), separated by a comma.
27. ___________ inheritance may lead to duplication of inherited members from a "grandparent" base class.
A. Multipath
B. Multiple
C. Multilevel
D. Hierarchical
View Answer
Ans : A
Explanation: Multipath inheritance may lead to duplication of inherited members from a "grandparent" base class.
28. C++ Inheritance relationship is?
A. Association
B. Is-A
C. Has-A
D. None of the above
View Answer
Ans : B
Explanation: Lets consider a relation ship between classes i.e. Dog IS A Animal, Apple IS A Fruit, Car IS A Vehicle etc. Here, IS A relationship is valid, but, if we say Animal IS A Dog, then it is wrong. So, Animal class should be the base class and Dog class will be the derived class.
29. Private members of the class are not inheritable.
A. TRUE
B. FALSE
C. May Be
D. Can't Say
View Answer
Ans : B
Explanation: None
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