C++ Interview Questions and Answers

What is C++?

C++ is an object-oriented programming language created by Bjarne Stroustrup in 1985.

What are the differences between C and C++?

C++ is a superset of C language.

C is a procedural programming language, but C++ supports both procedural and Object Oriented programming.

In C++ can use access modifier to restrict access of member function and variable to outside class and user, but in C we can’t do that.

What are the differences between C++ and Java?

C++ has pointers, but Java does not support pointer.
Java is platform-independent, but C++ is not.
Java has garbage collection, but C++ does not.
C++ used complier but Java uses interpreter.
C++ support operator overloading and multiple inheritance but Java not support both.

Explain is Object Oriented Programming (OOP)?

Object-oriented programming is a techniques for managing enormous complexity, achieving reuse of software components, and coupling data with the procedures that work on that data as a single "object"--a self-contained entity.

The basic concepts of Object Oriented Programming are given below:
Class and Object: Class is a template and implementation of entities whereas Object is variable and representation of class.
Encapsulation and data hiding: the binding of data and methods together called Encapsulation, where hide the data or direct access from outside known as data hiding.
Inheritance: Inheritance is concept of reusability and can used this to inherit the property of one class into another class.
Polymorphism: Poly means many, and morph means form. Polymorphism refers to the same name taking many forms or can perform different task depend on context.

What is a class in C++?

Class is a user-defined data type. It can consist of any combination of the variable types and also other class types.
The variables in the class are referred to as the member variables or data members and the functions in the class referred to as member Functions or methods of the class.

What is an object?

An object is an individual instance of a class and also called a class variable.
It can access the class members and functions by using the dot (.) operator.

Define the private, public and protected in C++?

Private, Public and protected and are three access specifier in C++.

Private: All members of a class data and methods are private by default. Private members can be accessed only within methods of the class itself.
Public: Public members can be accessed through any object of the class.
Protected: data members and member functions are only available to derived classes.

Explain constructor?

Constructors is special member function of class with the same name as the class and it used to create and initialize Object.
The constructor can take parameters as needed, but it cannot have a return value--not even void.
We can do Overloading of Constructor.

Explain destructor?

Destructors always has the name of the class, preceded by a tilde (~) and clean up allocated memory. Destructors take no arguments and have no return value.
We cannot Overload of destructor.

What is Default Constructors and Destructors?

If we don't declare a constructor or a destructor manually, the compiler makes one for you. The default constructor and destructor take no arguments and do nothing.

What is a copy constructor?

A copy constructor is the constructor which copies the exact values of one object's member variables into another object.
Copy constructors take one parameter, which a reference to an object of the same class.

Explain the static variable and member function?

Static variables and member functions belonging to the class rather than to the object. Normal member data is one per object, but static members are one per class and they can be called without having an object of that class.

 

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Height and Distance

An aeroplane flying at a height of 300 m above the ground passes vertically above another plane at an instant when the angles of elevation of the two planes from the same point on the ground are 60º and 45º respectively. What is the height of the lower plane from the ground?

From the top of a building 90 m high, the angles of depression of the top and the bottom of a tree are 30º and 45º respectively. What is the height of the tree?

Trigonometry

What is the value of sinx √( 1 /1+cosx + 1 /1-cosx ) ?

What is cos4 A - sin4 A / cos2 A - sin2 A equal to?

If 7sin2 x +3cos2 x = 4, 0 < x < 90º ,then what is the value of tan x?

If x = a cosθ + b sinθ and y = a sinθ - b cosθ then what is x2 + y2 equal to?

Average

The mean of 5 numbers is 15. If one more number is included, the mean of the 6 numbers becomes 17. What is the included number?

The mean marks obtained by 300 students in a subject are 60. The mean of top 100 students was found to be 80 and the mean of last 100 students was found to be 50. The mean marks of the remaining 100 students are?

In an asymmetrical distribution, of the mean and median of the distribution are 270 and 220 respectively, then the mode of the data is?

Let a, b, c, d, e, f, g be consecutive even numbers and j, k, l, m, n be consecutive odd numbers. What is the average of all the numbers?

Alligation or Mixture

25 kg of alloy X is mixed with 125 kg of alloy Y. If the amount of lead and tin in the alloy X is the ratio 1 : 2 and the amount of lead and tin in the alloy Y is in the ratio 2 : 3, then what is the ratio of lead to tin in the mixture?

Simplification

The ratio of two numbers is 1 : 5 and their product is 320. What is the difference between the square of these two numbers?

Trigonometry

What is the value of cot 4π/3 ?

Indian Politics

Article-24 of the Indian Constitution ‘Prohibition of employment of children in factories, etc’ deals with?

Article-134A of the Indian Constitution ‘Certificate for appeal to the Supreme Court’ deals with?

Chemistry

Who invented Aspirin?

Physics

A larger force on a rotating body results in larger?

What is the unit of the physical quantity, magnetic flux density?