C++ Programming

DERIVED CLASSES MCQs

Total Questions : 10

Question 1.

Which constructor will initialize the base class data member?


  1.    derived class
  2.    base class
  3.    class
  4.    None of the mentioned
 Discuss Question
Answer is Option B. -> base class

Because it is having the proper data set to initialize, Otherwise it will throw a error.

Question 2.


What is the output of this program?



1.
#include
2.
using namespace std;
3.
class X
4.
{
5.
int m;
6.
public:
7.
X() : m(10)
8.
{
9.
}
10.
X(int mm): m(mm)
11.
{
12.
}
13.
int getm()
14.
{
15.
return m;
16.
}
17.
};
18.
class Y : public X
19.
{
20.
int n;
21.
public:
22.
Y(int nn) : n(nn) {}
23.
int getn() { return n; }
24.
};
25.
int main()
26.
{
27.
Y yobj( 100 );
28.
cout
  1.    10 100
  2.    100 10
  3.    10 10
  4.    100 100
 Discuss Question
Answer is Option A. -> 10 100

In this program, We are passing the value and getting the result by derived class.
Output:
$ g++ der5.cpp
$ a.out
10 100

Question 3.

Which operator is used to declare the destructor?


  1.    #
  2.    ~
  3.    @
  4.    $
 Discuss Question
Answer is Option B. -> ~

None.

Question 4.


What is the output of this program?



1.
#include
2.
using namespace std;
3.
class Parent
4.
{
5.
public:
6.
Parent (void)
7.
{
8.
cout
  1.    10 100
  2.    100 10
  3.    10 10
  4.    100 100
 Discuss Question
Answer is Option A. -> 10 100

Answer:b
Explanation:In this program, We got an error in overloading because we didn’t invoke the 

destructor of parent.

Question 5.


What is the output of this program?



1.
#include
2.
using namespace std;
3.
class Base
4.
{
5.
public:
6.
int m;
7.
Base(int n=0)
8.
: m(n)
9.
{
10.
cout
  1.    10 100
  2.    100 10
  3.    10 10
  4.    100 100
 Discuss Question
Answer is Option A. -> 10 100

Answer:a
Explanation: In this program, We are printing the execution order of the program.
Output:
$ g++ der2.cpp
$ a.out
Instantiating Base
Base
Instantiating Derived
Base
Derived

Question 6.

Which of the following can derived class inherit?


  1.    members
  2.    functions
  3.    both a & b
  4.    None of the mentioned
 Discuss Question
Answer is Option C. -> both a & b

None.

Question 7.


What is the output of this program?



1.
#include
2.
using namespace std;
3.
class A
4.
{
5.
public:
6.
A(int n )
7.
{
8.
cout
  1.    54.3R
  2.    R4.35
  3.    4.3R5
  4.    None of the mentioned
 Discuss Question
Answer is Option A. -> 54.3R

In this program, We are passing the value and manipulating by using the derived class.
Output:
$ g++ der.cpp
$ a.out
54.3R

Question 8.


What is the output of this program?



1.
#include
2.
using namespace std;
3.
class BaseClass
4.
{
5.
protected:
6.
int i;
7.
public:
8.
BaseClass(int x)
9.
{
10.
i = x;
11.
}
12.
~BaseClass()
13.
{
14.
}
15.
};
16.
class DerivedClass: public BaseClass
17.
{
18.
int j;
19.
public:
20.
DerivedClass(int x, int y): BaseClass(y)
21.
{
22.
j = x;
23.
}
24.
~DerivedClass()
25.
{
26.
}
27.
void show()
28.
{
29.
cout
  1.    3 4
  2.    4 3
  3.    4
  4.    3
 Discuss Question
Answer is Option B. -> 4 3

In this program, We are passing the values and assigning it to i and j and we are printing it.
Output:
$ g++ der1.cpp
$ a.out
4 3

Question 9.

Where is the derived class is derived from?


  1.    derived
  2.    base
  3.    both a & b
  4.    None of the mentioned
 Discuss Question
Answer is Option B. -> base

Because derived inherits functions and variables from base.

Question 10.

Pick out the correct statement.


  1.    A derived class's constructor cannot explicitly invokes its base class's constructor.
  2.    A derived class's destructor cannot invoke its base class's destructor.
  3.    A derived class's destructor can invoke its base class's destructor.
  4.    None of the mentioned
 Discuss Question
Answer is Option B. -> A derived class's destructor cannot invoke its base class's destructor.

Destructors are automatically invoked when a object goes out of scope or when a dynamically 

allocated object is deleted. Inheritance does not change this behavior. This is the reason a 

derived destructor cannot invoke its base class destructor.