250+ TOP MCQs on Private Access Specifier and Answers

class student
{  
	private: student()
	{  
	}
	public : student( int x) 
	{ 
		marks =x; 
	}
};

class A
{
	private : int marks; char name[20];
	public :
	A(int x=100)
	{ 
		marks=x;  
	}
};

class A
{
	private : int sum(int x, int y)
	{ 
		return x+y; 
	}
	public: A()
	{  
	}
	A(int x, int y)
	{ 
		cout<<sum(x,y);  
	}
};

Answer: d
Clarification: Constructor is not having any default arguments hence no default value will be given to any parameters. Only integer values must be passed to the constructor if we need the sum as output, otherwise if float values are passed, type mismatch will be shown as error.

9. Which member will never be used from the following class?

class A()
{ 
	int marks; char name[20];
	public : A()
	{ 
		marks=100; 
	}
	void disp()
	{ 
		cout<<”Marks= ”&lt'

a) name variable will never be used
b) marks variable will never be used
c) constructor will never be used
d) disp() function will never be used
Answer: a
Clarification: Variable name will never be used. It is a private member. None other than class members can access name, also, neither the constructor nor the disp() function are accessing the variable name. Hence it will never be accessible.

10. Private member functions can be overloaded.
a) True
b) False
Answer: a
Clarification: The private functions can also be overloaded. This can be done in usual way by having the same name of the member function and having different signature. Only thing is, they must be accessed from members of class only.

11. Which among the following is true?
a) Private member functions can’t be overloaded
b) Private member functions can be overridden
c) Private member functions can’t be overloaded with a public member
d) Private member function can’t be overridden
Answer: d
Clarification: The private member functions can be overloaded but they can’t be overridden. This is because, overriding means a function with same name in derived class, gets more priority when called from object of derived class. Here, the member function is private so there is no way that it can be overridden.

12. Which data member in following code will be used whenever an object is created?

Class A
{ 
   int x; int y; int z;
   public : A()
   { 
      y=100; x=100*y; 
   }
};

a) x will be used
b) y will be used
c) z will be used
d) All will be used
Answer: c
Clarification: Whenever an object will be created, the constructor will be called. Inside constructor we are using the data members x and y. Hence these two will always be used with each object creation.

13. Which member can be considered most secure in the code below?

class A()
{
	int a;
	private : int b;
	protected : int c;
	public : int d;
};

a) a
b) b
c) c
d) d
Answer: b
Clarification: The default variables can be inherited in some special cases but the public members can never be inherited. Hence the most secure data member in the class is b.

14. Which among the following is correct for the code given below?

class A
{
	private : A()
	{ 
	}
	public : A(int x)
	{  
	}
};
A a;
A b(100);

a) Program will give compile time error
b) Program will run fine
c) Program will give runtime error
d) Program will give logical error
Answer: a
Clarification: The program will be giving a compile time error as the default constructor is private in class. And, the logical errors are usually runtime so we can’t say that the program will give logical error. The program will not run.

15. Which among the following is correct?
a) Private specifier must be used before public specifier
b) Private specifier must be used before protected specifier
c) Private specifier must be used first
d) Private specifier can be used anywhere in class
Answer: d
Clarification: The private specifier can be used anywhere in the class as required. It is not a rule to mention the private members first and then others. It is just followed to write first for better readability.