C++ Notes By Yatendra Kashyap

EXPECTED VIVA QUESTIONS 1.

What is a class?

Class is concrete representation of an entity. It represents a group of objects, which hold similar attributes and behavior. It provides Abstraction and Encapsulations. Classes are generally declared using the keyword class. 2.

What is an Object? What is Object Oriented Programming? Object represents/resembles a Physical/real entity. An object is simply something you can give a name. Object Oriented Programming is a Style of programming that represents a program as a system of objects and enables code-reuse. Object is a software bundle of variables and related methods.

Objects have state and behavior. object is a real life entity which contains data and functions to operate on that data. 3.

What is Encapsulation? Encapsulation is binding of attributes and behaviors. Hiding the actual implementation and exposing the functionality of any object. Encapsulation is the first step towards OOPS, is the procedure of covering up of data and functions into a single unit (called class). Its main aim is to protect the data from out side world

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What is Abstraction? Hiding the complexity. It is a process of defining communication interface for the functionality and hiding rest of the things.

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What is Overloading? Adding a new method with the same name in same/derived class but with different number/types of parameters. It implements Polymorphism.

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What is Inheritance? It is a process in which properties of object of one class acquire the properties of object of another class.

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What is an Abstract class? An abstract class is a special kind of class that cannot be instantiated. It normally contains one or more abstract methods or abstract properties. It provides body to a class.

8. What is Polymorphism? And its type? Poly" means "many" and "morph" means "form". Polymorphism is the ability of an object (or reference) to assume (be replaced by) or become many different forms of object. Example: function overloading, function overriding, virtual functions. Another example can be a plus? +? sign, used for adding two integers or for using it to concatenate two strings There are two types of polymorphism1)Run time polymorphism –Address of the function determine at the runtime is

known as runtime polymorphism 2) Compile time polymorphism- Address of the function determine at the compile time is known as runtime polymorphism 9. What do you mean by iostream.h? 10 What is inheritance and its type? 11 What is the difference between c and c++?

12. What are the differences between a class and an object? Ans: Object is an instance of a class. The class is a blueprint of all the objects which Share common properties and the behavior. Class represents the abstract data type and Object is a real-world entity. 12 What are the differences between a structure and a class? Ans: There is no difference in structure and a class except that class members are private by default and structure members are public by default. 13 What is the difference b/n public, private and protected? 1. Public: The data members and methods having public as access outside the class. 2. Protected: The data members and methods declared as protected will be accessible to the class methods and the derived class methods only.

3. Private: These data members and methods will be accessible not from objects created outside the class. 14 What is the difference b/n variable declaration and definition?

Definition Ex - int a=5 Tell the compiler about the variable: its type and name, as well as allocated a memory cell for the variable Declaration Ex- int a Describe information ``about'' the variable, variable, doesn’t allocate memory cell for the variable

15 What is a void return type?

A void return type indicates that a method does not return a value.

16What is the difference between a while statement and a do statement? A while loop is a entry control loop .A do while loop is a exit control loop, in this loop at least one time a condition is executed always and it also terminated with semicolon.

What is a nested class? Why can it be useful? A nested class is a class enclosed within the scope of another class. For example: // Example 1: Nested class // class Outer Class {class Nested Class {// …}; //...

17What is inline function? Normally, a function call transfers the control from the calling program to the function and after the execution of the program returns the control back to the calling program after the function call. These concepts of function saved program space and memory space are used because the function is stored only in one place and is only executed when it is called. This concept of function execution may be time consuming since the registers and other processes must be saved before the function gets called. The extra time needed and the process of saving is valid for larger functions. If the function is short, the programmer may wish to place the code of the function in the calling program in order for it to be executed. This type of function is best handled by the inline function. In this situation, the programmer may be wondering “why not write the short code repeatedly inside the program wherever needed instead of going for inline function?” Although this could accomplish the task, the problem lies in the loss of clarity of the program. If the programmer repeats the same code many times, there will be a loss of clarity in the program. The alternative approach is to allow inline functions to achieve the same purpose, with the concept of functions.

18 What is the difference between overloading and overriding? Overloading - Two functions having same name and return Type, but with different type and/or number of arguments. Overriding - When a function of base class is re-defined in the derived class. 19 What is array and its type? 20 What is the difference b/n array and pointer? Pointer –pointer is a variables that hold the address of another variable .It is used to manipulate data using the address, pointer use the * operator to access the data pointed by them. Array –array use subscripted [] variable to access and manipulate the data ,array variables can be equivalently written using pointer expression.

Tokens - The smallest individual units in a program are known as tokens, c++ has the following tokens: Example of tokens: - }, {, “ “, int  Keywords  Identifiers  Constants Identifier: In our everyday, we give names to different things so they can be Referred easily. Similarly, in C+, we use identifiers to name user created entities Which may be?

• •

Variable Function

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Type e.g. a class

21 What is default Constructor? Constructor with no arguments or all the arguments has default values. In Above Question Test() is a default constructor

22 What is friend function? As the name suggests, the function acts as a friend to a class. As a friend of a class, it can access its private and protected members. A friend function is not a member of the class. But it must be listed in the class definition. 23 What is a scope resolution operator? A scope resolution operator (::), can be used to define the member functions of a class outside the class. 24 What do you mean by pure virtual functions? A pure virtual member function is a member function that the base class forces derived classes to provide. Normally these member functions have no implementation. Pure virtual functions are equated to zero. class Shape { public: virtual void draw() = 0; }; 25 What are the advantages of inheritance? It permits code reusability. Reusability saves time in program development. It encourages the reuse of proven and debugged high-quality software, thus reducing problem after a system becomes functional 26 What are virtual functions? Describe a circumstance in which virtual functions would be appropriate Virtual functions are functions with the same function prototype that are defined throughout a class hierarchy. At least the base class occurrence of the function is preceded by the keyword virtual. Virtual functions are used to enable generic processing of an entire class hierarchy of objects through a base class pointer. For example, in a shape hierarchy, all shapes can be drawn. If all shapes are derived from a base class Shape which contains a virtual draw function, then generic processing of the hierarchy can be performed by calling every shape’s draw generically through a base class Shape pointer.

27 Distinguish between virtual functions and pure virtual functions A virtual function must have a definition in the class in which it is declared. A pure virtual function does not provide a definition. Classes derived directly from the abstract class must provide definitions for the inherited pure virtual functions in order to avoid becoming an abstract base class

28 What is the difference between parameter and arguments? Parameter –While defining method, variable passed in the method are called parameters. Arguments-While using those methods value passed to those variables are called arguments.

29 What are the different types of parameters? There are two types of parameters associated with functions. they are: (a) Actual parameter: The parameters associated with function call are called actual parameters. (b) Formal parameter: The parameters associated with the function definition are called formal parameters.

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Keywords:

Keywords are predefined reserved identifiers that have special meanings. They cannot be used as identifiers in your program. Keyword is a word that the compiler already knows, i.e. when the compiler sees a keyword somewhere in the program it knows what to do automatically. For example, when the compiler encounters the keyword ‘int’, it knows that ‘int’ stands for an integer. Or if the compiler reads a ‘break’, then it knows that it should break out of the current loop. 31 What are the common Data types?and its range?

keyword Char int long float double

Range (low) -128 -32768 -2147483648 3.4 x 10-38 1.7 x 10-308

(high) 127 32767 2147483647 3.4 x 1038 1.7 x 10308

Bytes of memory(size) 1 2 4 4 8

30 what is the Syntax of for loop?

for (initillization; condition;increment) 32.Explain the different types of parameter passing. types of parameter passing in C++. They are: (a) Call by value: In this method, the actual parameters are copied into the

Formal parameters and the change in the formal parameters do not affect the actual parameter. In this passing only the value so that copy of the value is sent to function, original value will not change. (b) Call by reference: In this mode of parameter passing instead of passing the Value to a function, a reference or an alias to the actual parameter is passed. The changes made in the formal parameters are reflected in the actual parameters. In this ,address of the value is passed ,so the original value will be change .

33 what is the use of getch() function in a program.difference b/w getch() and getche()? getch() returns to the program after hitting any key. getche() waits for the character, read it and then returns to the program