C++ Programming Questions and Answers – Derivation and Templates

C++ interview questions focuses on “Derivation and Templates”. One shall practice these advanced C++ questions to improve their C++ programming skills needed for various interviews (campus interviews, walkin interviews, company interviews), placements, entrance exams and other competitive exams. These questions can be attempted by anyone focusing on learning C++ programming language. They can be a beginner, fresher, engineering graduate or an experienced IT professional. Our advanced C++ questions come with detailed explanation of the answers which helps in better understanding of C++ concepts.
C++ interview questions on “Derivation and Templates” along with answers, explanations and/or solutions:

Q 1. Which is dependant on template parameter?
A. method
B. abstract class
C. base class
D. static class

Show Answer

Answer:-C. base class

Explanation

Base class is dependant on template parameter.

Q 2. Which value is placed in the base class?
A. derived values
B. default type values
C. null value
D. both default type & derived values

Show Answer

Answer:-B. default type values

Explanation

We can place the default type values in a base class and overriding some of them through derivation.

Q 3. How many bits of memory needed for internal representation of class?
A. 1
B. 2
C. 4
D. no memory needed

Show Answer

Answer:-D. no memory needed

Explanation

classes that contain only type members, nonvirtual function members, and static data members do not require memory at run time.

Q 4. What will be the output of the following C++ code?

#include <iostream>
using namespace std;
class class0
{
public:
virtual ~class0(){}
protected:
char p;
public:
char getChar();
};
class class1 : public class0
{
public:
void printChar();
};
void class1::printChar()
{
cout << “True” << endl;
}
int main()
{
class1 c;
c.printChar();
return 1;
}
A. True
B. error
C. no output
D. runtime error

Show Answer

Answer:-A. True

Explanation

In this program, We are passing the values and inheriting it to the other class and printing the result. $ g++ dert.cpp $ a.out True

Q 5. What will be the output of the following C++ code?

#include <iostream>
using namespace std;
template<typename T>class clsTemplate
{
public:
T value;
clsTemplate(T i)
{
this->value = i;
}
void test()
{
cout << value << endl;
}
};
class clsChild : public clsTemplate<char>
{
public:
clsChild(): clsTemplate<char>( 0 )
{
}
clsChild(char c): clsTemplate<char>( c )
{
}
void test2()
{
test();
}
};
int main()
{
clsTemplate <int> a( 42 );
clsChild b( ‘A’ );
a.test();
b.test();
return 0;
}
A. 42
B. A
C. 42 A
D. A 42

Show Answer

Answer:-C. 42 A

Explanation

In this program, We are passing the values by using the template inheritance and printing it. Output: $ g++ dert.cpp $ a.out 42 A

Q 6. What will be the output of the following C++ code?

#include <iostream>
using namespace std;
template <class T>
class A
{
public:
A(int a): x(a) {}
protected:
int x;
};
template <class T>
class B: public A<char>
{
public:
B(): A<char>::A(100)
{
cout << x * 2 << endl;
}
};
int main()
{
B<char> test;
return 0;
}
A. 100
B. 200
C. error
D. runtime error

Show Answer

Answer:-B. 200

Explanation

In this program, We are passing the values and manipulating it by using the template inheritance. Output: $ g++ dert2.cpp $ a.out 200

Q 7. What will be the output of the following C++ code?

#include <iostream>
using namespace std;
template <class type>
class Test
{
public:
Test();
~Test();
type Data(type);
};
template <class type>
type Test<type>::Data(type Var0)
{
return Var0;
}
template <class type>
Test<type>::Test()
{
}
template <class type>
Test<type>::~Test()
{
}
int main(void)
{
Test<char> Var3;
cout << Var3.Data(‘K’) << endl;
return 0;
}
A. k
B. l
C. error
D. runtime error

Show Answer

Answer:-A. k

Explanation

In this program, We are passing the values and printing it by using template inheritance. Output: $ g++ dert3.cpp $ a.out k

Q 8. What will be the output of the following C++ code?

#include <iostream>
using namespace std;
class Base
{
public:
Base ( )
{
cout << “1” << endl;
}
~Base ( )
{
cout << “2” << endl;
}
};
class Derived : public Base
{
public:
Derived ( )
{
cout << “3” << endl;
}
~Derived ( )
{
cout << “4” << endl;
}
};
int main( )
{
Derived x;
}
A. 1234
B. 4321
C. 1423
D. 1342

Show Answer

Answer:-D. 1342

Explanation

In this program, We are printing the order of execution of constructor and destructor in the class. Output: $ g++ dert4.cpp $ a.out 1342

Q 9. How many kinds of entities are directly parameterized in c++?
A. 1
B. 2
C. 3
D. 4

Show Answer

Answer:-C. 3

Explanation

C++ allows us to parameterize directly three kinds of entities through templates: types, constants, and templates.

Q 10. How many kinds of parameters are there in C++?
A. 1
B. 2
C. 3
D. 4

Show Answer

Answer:-C. 3

Explanation

There are three kinds of parameters are there in C++. They are type, non-type, template.