C++ Friend Functions MCQ -1 (MULTIPLE CHOICE QUESTIONS)

We have already covered C++ Friend Functions questions in the last set of MCQs. There, we have discussed some good questions. This set of MCQ(multiple choice questions focuses) on the C++ Friend Functions questions.

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C++ MCQ | FRIEND FUNCTIONS

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C++ Friend Functions MCQ Questions

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

#include <iostream>
    using namespace std;
    class Box
    {
        double width;
        public:
        friend void printWidth( Box box );
        void setWidth( double wid );
    };
    void Box::setWidth( double wid )
    {
        width = wid;
    }
    void printWidth( Box box )
    {
        box.width = box.width * 2;
        cout << "Width of box : " << box.width << endl;
    }
    int main( )
    {
        Box box;
        box.setWidth(10.0);
        printWidth( box );
        return 0;
   }

a) 40
b) 20
c) 5
d) 10

Show Answer

2. What will be output for the following code?

class Box
{
 int capacity;
   public:
 void print();
 friend void show();
 bool compare();
 friend bool lost();
};

a) 1
b) 2
c) 3
d) 4

Show Answer

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

#include <iostream>
#include <string>
using namespace std;
class Box
{
	int capacity;
    public:
	Box(int cap){
		capacity = cap;
	}
 
	friend void show();
};
 
void show()
{	
	Box b(10);
	cout<<"Value of capacity is: "<<b.capacity<<endl;
}
 
int main(int argc, char const *argv[])
{
	show();
	return 0;
}

a) Value of capacity is: 10
b) Value of capacity is: 100
c) Segmentation fault
d) Error

Show Answer

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

#include <iostream>
#include <string>
using namespace std;
class Box
{
	int capacity;
    public:
	Box(int cap){
		capacity = cap;
	}
	friend void show();
};
 
void Box::show()
{	
	Box b(10);
	cout<<"Value of capacity is: "<<b.capacity<<endl;
}
 
int main(int argc, char const *argv[])
{
	show();
	return 0;
}

a) Value of capacity is: 10
b) Value of capacity is: 100
c) Segmentation fault
d) Error

Show Answer

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

#include <iostream>
    using namespace std;
    class sample
    {
        private:
        int a, b;
        public:
        void test()
        {
            a = 100;
            b = 200;
        }
        friend int compute(sample e1);
    };
    int compute(sample e1)
    {
        return int(e1.a + e1.b) - 5;
    }
    int main()
    {
        sample e;
        e.test();
        cout  << compute(e);
        return 0;
    }

a) 100
b) 200
c) 295
d) 300

Show Answer

6. Predict the output of following program.

#include <iostream>
using namespace std;
class A
{
protected:
    int x;
public:
    A() {x = 0;}
    friend void show();
};
 
class B: public A
{
public:
    B() : y (0) {}
private:
    int y;
};
 
void show()
{
    A a;
    B b;
    cout << "The default value of A::x = " << a.x << " ";
    cout << "The default value of B::y = " << b.y;
}

a) Compiler Error in show() because x is protected in class A
b) Compiler Error in show() because y is private in class b
c) The default value of A::x = 0 The default value of B::y = 0
d) Compiler Dependent

Show Answer

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

#include <iostream>
#include <string>
using namespace std;
class B
{
	int b;
   public:
	B(int i){
		b = i;
	}
};
 
class C
{
	B b;
    public:
	C(int i){
		b = B(i);
	}
	friend void show();
};
 
void show()
{
	C c(10);
	cout<<"value of b is: "<<c.b.b<<endl;
}
 
int main(int argc, char const *argv[])
{
	show();
	return 0;
}

a) value of b is: 12345435
b) value of b is: 10
c) segmentation fault
d) error

Show Answer

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

#include <iostream>
#include <string>
using namespace std;
class B
{
	int b;
    public:
	B(){}
	B(int i){
		b = i;
	}
	int show(){
		return b;
	}
};
 
class C
{
	B b;
    public:
	C(int i){
		b = B(i);
	}
	friend void show(){
 
		C c(10);
		cout<<"value of b is: "<<c.b.show()<<endl;
	}
};
 
int main(int argc, char const *argv[])
{
	C c(1);
	c.show();
	return 0;
}

a) value of b is: 12345435
b) value of b is: 10
c) segmentation fault
d) error

Show Answer

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

#include <iostream>
    using namespace std;
    class sample 
    {
        int width, height;
        public:
        void set_values (int, int);
        int area () {return (width * height);}
        friend sample duplicate (sample);
    };
    void sample::set_values (int a, int b) 
    {
        width = a;
        height = b;
    }
    sample duplicate (sample rectparam)
    {
        sample rectres;
        rectres.width = rectparam.width * 2;
        rectres.height = rectparam.height * 2;
        return (rectres);
    }  
    int main ()  
    {
        sample rect, rectb;
        rect.set_values (2, 3);
        rectb = duplicate (rect);
        cout << rectb.area();
        return 0;
    }

a) 20
b) 24
c) 18
d) 16

Show Answer

10. Predict the output the of following program.

#include <iostream>
using namespace std;
 
class B;
class A {
    int a;
public:
    A():a(0) { }
    void show(A& x, B& y);
};
 
class B {
private:
    int b;
public:
    B():b(0) { }
    friend void A::show(A& x, B& y);
};
 
void A::show(A& x, B& y) {
    x.a = 10;
    cout << "A::a=" << x.a << " B::b=" << y.b;
}
 
int main() {
    A a;
    B b;
    a.show(a,b);
    return 0;
}

a) Compiler Error
b) A::a=10 B::b=0
c) A::a=0 B::b=0
d) None

Show Answer

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