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HCL Technical Interview Questions

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HCL Technical Interview Questions

1) Does every class have a Constructor?

Yes, every class needs a Constructor. It may be Parameterized or Default. If the user does not define a constructor within a class, the default constructor is always included in that code.

The objective of Constructor is to initialize an object called object initialization. Constructors are mainly created for initializing an object.

2) How Java enable High Performance?

Java uses a Just-In-Time Compiler to enable high performance. Just-In-Time Compiler is a program that turns Java bytecode, which is a program that contains an instruction that must be interpreted into instruction that can be sent directly to the processor.

3) Why is java considered as dynamic?

It is designed to change the evolving environment. Java can carry an extensive amount of runtime information that can be used to verify and resolve access to the object at runtime.

4) What is joins in SQL?

Joins is nothing but connecting two or more table to fetch the record from two or more databases.

5) Can we have Private Constructor in Java?

Private Constructor is used if you do not want other class to instantiate the object. Private Constructor is used in Singleton design Pattern, Factory Method Design Pattern.

6) Differentiate Between Primary Key and Unique Key.

Primary Key	Unique Key
1. In a Primary key, there should be only one primary key in a table.	1. In A Unique key, there can be more than one unique key in a table.
2. Primary key will block duplicate value and a null value.	2. Unique key will block duplicate value and accept a null value.

7) Differentiate between Method Overloading and Method Overriding.

Method Overloading	Method Overriding
1. Method Overloading is used to gain the readability of the program.	1. Method Overriding is used to provide the specific implementation of the method that already provided by the superclass.
2. In the case of Method Overloading, the parameter must be different.	2. In the case of Method Overriding, the parameter must be equal.
3. Overloading happens at Compile time.	3. Overriding happens at runtime.
4. The Return type of method does not matter in case of method overloading it can be the same or different.	4. In the case of method Overriding, the return type must be the same.
5. you can overload a static, final and private method in Java	5. You cannot override a static, final and private method in Java.

8) What is the purpose of finalize () method in Java?

Finalize () method in java is a special method much like the main method in java. Finalize () method is called before garbage collector reclaims the object, its last chance for any object to perform clean up activity i.e. releasing any fixed order resources held, terminating connection if open etc.

9) Why can static method not override?

A static method cannot override because the static method is bound with class whereas instance method is bound with an object. Static method belongs to the class area and Instance method belong to the heap area.

10) What is singleton Class?

Singleton Class limited the number to one but allowing the flexibility to create more object if the situation changes.

11) Can we override java main method?

No, because main is a Static Method.

12) What is Class Cast Exception?

Class Cast Exception is thrown by java when you try to cast an object of one data type to another data type. Java allows us to cast the variable of one type to another as long as the casting happens between compatible data type.

13) Why polymorphism is used in Java?

The good reason for why polymorphism is a need in Java because the concept is extensively used in implementing inheritance. It plays an important role in allowing the object having a different internal structure to share the same external interface.

14) What is an Abstract class?

An Abstract class is one that is not used to create an object. It is only used as base class for the other class. The Abstract class is always public or friendly.

Syntax:

public abstract class class_name
        {
            //class member
        }

15) Can I have Private Constructor in Abstract Class?

Abstract Class can have Private Constructor But that class cannot be extended by another class. Alternatively, of adding a static inner class inside the Abstract Class and extends that Abstract Class.

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Cognizant Technical Interview & Programming Questions

by Team IM | Jan 25, 2022 | Any Branch, Any Degree, Bangalore, Batch 2017, Batch 2018, Batch 2019, Batch 2020, Batch 2021, Batch 2022, BCA Job, Blog, Branch CIVIL, Branch CSE, Branch ECE, Branch EEE, Branch EN, Branch IT, Branch ME, BTech Job, Cognizant, Companies Recruitment Notifications, Govt. Jobs, Govt. Jobs Notifications, Internships, Interview Preparation, IT Jobs, MCA Job, Miscellaneous, Pune, Technical

Cognizant Technical Interview Questions

Questions mainly asked from:

C Theory/Programs
C++ or Java
OOPS
Software Engineering
Optional – DBMS, Operating Systems, Data Structures

Cognizant C Programming Interview Questions

1) What is a pointer? Define it.

Pointer is a variable which stores the address of other variables which hold some value in it. Directly pointer is used to point values of variables indirectly. We can manipulate its values.

2) What is a dangling pointer in C?

Dangling pointer is a pointer which does not point to a valid object of the appropriate type. It appears when a pointer is in the stack but not in the memory in a heap. Char *p =NULL; A dangling pointer attempt to deallocate without allocating space will result in a segmentation fault.

Dangling pointers arise during object destruction, when an object that has an incoming reference is deleted or deallocated, without changing the data of the pointer, so that the pointer points to the memory location of the deallocated memory.

3) What is a memory leak in a heap?

When there is a space area in a heap, but no variable is in the stack pointing to that memory.

4) What is a data type?

Data Type defines the type of value which are allocated by us to a variable and have a range in between we assign values. E.g., “Int” it is a data type which able to store data between “-32768 to +32768” in C.

5) What is the size of the integer data type?

Size of it is 2 Byte or 4 Byte.

6) What is malloc?

Allocates requested size of bytes and returned a pointer first byte of allocated space. Malloc is using for dynamic memory allocation.

Syntax:

ptr = (cast-type*) malloc(byte-size)

7) What is a string?

A string is a sequence of characters. It can be defined using the array or by using String header file.

8) “/0” in a string?

This symbol shows the ending of the string.

E.g. char a[] = {“s”,”e”,”t”,”/0″};.

9) What is recursion?

The process by which a method calls itself directly or indirectly, again and again, is called recursion and the corresponding function.

10) What is the difference between a pre-increment operator and post-increment operator?

Pre-increment operator used incrementing the variable value by one before assigning the cost to the variable. Post-increment operator use to incrementing the variable value by one after assigning the value to the variable.

11) What are the key features or characteristics OFC language?

Reliability
Portability
Flexibility
Interactivity
Modularity
Efficiency and Effectiveness

12) What is embedded C?

Embedded C is the extension of C programming language.

Embedded C is used to develop microcontroller-based applications.

Embedded C includes features not available in standard C like fixed-point arithmetic, named address spaces, and necessary I/O hardware addressing.

Cell phones, MP3 players are some example of embedded systems in which integrated C is used to program and control these devices.

13) Which level is C language belonging?

C language is belonging to middle-level language. C language behaves as a bridge between machine level (low level) languages and high-level languages.

C language is more user-friendly than machine level languages. And, C language does not support all the concepts that high-level languages offer. So, C programming language called as middle-level language.

14) What is the difference between structured oriented, object-oriented and non-structure oriented programming language?

Structured oriented programming language –

In this type of language, large codes fragmented into small programs called functions.
The main focus is on procedures and functions that operate on values
Data moves without any restrictions around the systems from one procedure to another
Program structure follows “Top-Down Approach.”
Example: C, Pascal, ALGOL, and Modula-2

Object-oriented programming language –

In this type of language, programs fragmented into objects
The main focus is on the data/values that are manipulating and not on the procedures or functions.
Data is hidden from functions and cannot access by external functions
Program structure follows the “Bottom UP Approach.”
Example: C++, and C# (C sharp)

Non-structure oriented programming language –

There is no specific structure rule for programming this language.
Example: BASIC, COBOL, FORTRAN

14) What is modifier in C?

Modifiers derive the space to allocate for a variable.

Modifiers are fixed with basic data types to modify (either increase or decrease) the amount of storage allocated to a variable.

For example, storage requirements for int data type are 4 bytes for a 32-bit processor. We can increase range by using long int data type which is 8 byte. We can decrease the range by using short int which is 2 byte.

15) What is the difference between variable declaration and variable definition in C?

Variable declaration tells the compiler about data type and size of the variable. Whereas, variable definition allocates memory to the variable

Variable can be declared many times in a program. But, the definition can happen only one time for a variable in a program.

Variable declaration is for assignment of properties and identification to a variable. Whereas, a variable definition is for assignments of storage space to a variable

Cognizant OOPs Interview Questions

1) What are virtual Functions?

In object-oriented programming, in languages such as C++, and Object Pascal, a virtual function or virtual method is an inheritable and overrideable function or method for which dynamic dispatch facilitated. This concept is an essential part of the (runtime) polymorphism portion of object-oriented programming (OOP).

2) What is overloading in OOPs?

Overloading is a process used to avoid redundant code where the same method name used multiple times but with a different set of parameters. The actual method that gets called during runtime is resolved at compile time, thus avoiding runtime errors.

3) What is overriding?

In any object-oriented programming, Overriding is a process that allows a child class or subclass to provide a specific implementation of functions that is already provided by one of its super-classes or parent classes.

4) What is polymorphism?

By using the ability of polymorphism an object can take on multiple types. The frequent use of polymorphism occurs when a parent class refers to an object of the child class. The Java object that can pass more than one IS-A test is polymorphic.

5) What is data abstraction?

In oops, abstraction is one of three main principles (along with encapsulation and inheritance). Through the process of abstraction, a programmer hides all but the relevant data about an object to reduce complexity and increase efficiency.

6) What is encapsulation?

Encapsulation is one of the primary concepts in object-oriented programming. It describes the idea of combining data in a single class and methods that work on that data, e.g., a class which is a blueprint in java. This concept is also often used to preserve the internal state, of an object from the outside.

7) What is Inheritance in java?

In object-oriented programming, inheritance helps new objects to take on the properties of old objects. A class that uses for inheritance is called a base class or superclass. A class that inherits data from a base class is called a subclass or derived class

8) What is the constructor?

A constructor is a method which is used to initialize a newly created object and is called just after when memory allocated to the object. It can be used to implement the objects to desired values or default values at the time of object creation.

9) What is the destructor?

A destructor used when the initialized object is destructing it called automatically during the destruction of an object. It helps in recovering the heap space and remove files.

Cognizant Data structure Interview Questions

1) What is a Data Structure?

Data Structure is a process in which management or organization of data that enable a more efficient way to organize the data.

2) What have linked lists?

A linked list is a set of ordered data and each of its previous nodes connected to its succeeding node. It is like an array but more efficient then array because we can insert or delete data in between the nodes.

3) Is the array of data structure?

Yes, because it also handles the data in a structured way.

4) Define a binary search Tree?

It is also known as ordered or sorted binary tree. It keeps there nodes or keys in sort form, and the root node of BST is bigger than the left node and smaller than the right node.

5) What is a Binary Tree in the data structure?

A binary tree is part of a data structure that has two sub-nodes, a right node, and a left node. In programming, binary trees are an advanced version of the linked list.

6) What is the dissimilarity between Push and Pop methods of the stack?

Pushing and popping applies to the way data is stored and fetched from a stack. A push method denotes data being added to it, meaning information is being “pushed” in the stack. On the other hand, a pop method denotes data retrieval/fetch, and in particular, refers to the first data is being fetched.

7) What is the dissimilarity between a stack and the array?

A stack base on LIFO pattern. It means that data access follows a sequential process wherein the last data to be entered when the first one deleted. Arrays do not follow a particular order and instead can access by referring to the indexed element within the array.

8) What are doubly linked Lists?

Doubly linked lists are a particular part of linked list wherein traversal across the data elements can be done in any directions. This is possible by having two links in every node, one that connects to the next node and another one that links to the previous node.

9) What is a queue data structure?

A Queue is a data structure which is linear and follows a fixed order in which the operations occur. The order is always First In First Out (FIFO). An excellent example of a queue is any queue of the customer for a resource where the customer that came first served first. The difference between stacks and queues is while deleting.

10) What is a stack data structure?

Basic features of Stack are an ordered list of the similar data type. The stack is LIFO (Last In First Out) data structure, or we can say FILO (First In Last Out) data structure. Push () method is used to insert/enter new elements into the Stack and pop() method is used to remove/delete an element from the stack.

11) What is a graph in the data structure?

A graph shows a representation of a set of objects/nodes where some pairs of object/nodes are connected by links/connection. The interconnection of objects are represented by points termed as vertices, and the links that connect the vertices are called edges.

12) What is a priority queue?

A priority queue is an abstracted data type which is like a queue or stack data structure, but where additionally each element has a “priority” associated with it. In a priority queue, an element with high priority is served before an element with low priority.

13) Show the time complexity of the linked list during insertion?

The time complexity of insertion/deletion in a singly linked list depends upon the position where you want to perform them. For example, if you want to insert an element at the end of the linked list, then you have to traverse/travel the entire list, and hence the complexity will be O(n).

Cognizant Programming Questions

1) Write a program to reverse any number.

This code below is written in Java.

package javaapplication6;
import java.util.Scanner;
public class JavaApplication6 {
    public static void main(String[] args)
    {
        int i, temp, sum=0, n;
        Scanner sc = new Scanner(System.in);
        n=sc.nextInt();
        temp=n;
        while(n>0)
        {
            int r = n%10;
            sum = sum*10+r;
            n = n/10;
        }
        System.out.println(“Reverse of Number is:-“ +sum);
        if(temp==sum)
        {
            System.out.println(“Palindrom”);
        }
        else
        {
            System.out.println(“Not Palindrom”);
        }
    }
}

2) Write a program to find out some of the digits of the given number.

package javaapplication6;
import java.util.Scanner;
public class JavaApplication6 {
    public static void main(String[] args)
    {
        int i, temp, sum=0, n;
        Scanner sc = new Scanner(System.in);
        n=sc.nextInt();
        temp=n;
        while(n>0)
        {
            int r = n%10;
            sum = sum+r;
            n = n/10;
        }
        System.out.println(“Reverse of Number is:-“ +sum);
    }
}

3) Write a program to find out the power of a number.

package javaapplication6;
import java.util.Scanner;
public class JavaApplication6 {
public static void main(String[] args)
    {
        int result=1, n;
        Scanner sc = new Scanner(System.in);
        System.out.println(“the Exoponent is:- “);
        n=sc.nextInt();
        System.out.println(“the base is:- “);
        int base = sc.nextInt();
        while (n != 0)
    {
        result *= base;
        –n;
    }
        System.out.println(“Power of Number is:-“ +result);
    }
}

4) Write a program to add two numbers without using the addition operator.

package javaapplication6;
import java.util.Scanner;
public class JavaApplication6 {
   static int Add(int x, int y)
    {
        while (y != 0)
        {
            int carry = x & y;
            x = x ^ y;
            y = carry << 1;
        }
        return x;
    }
    public static void main(String arg[])
    {
        Scanner sc = new Scanner(System.in);
        System.out.println(“First value is:- “);
        int a=sc.nextInt();
        System.out.println(“Second value is:- “);
        int b=sc.nextInt();
        System.out.println(“Sum of both digits:- “+Add(a, b));
    }
}

5) Write a program to subtract two numbers without using a subtraction operator.

package javaapplication6;
import java.util.Scanner;
     public class JavaApplication6 {
   static int Add(int x, int y)
    {
        while (y != 0)
        {
            int borrow = ~ x & y;
            x = x ^ y;
            y = borrow << 1;
        }
        return x;
    }
    public static void main(String arg[])
    {
        Scanner sc = new Scanner(System.in);
        System.out.println(“First value is:- “);
        int a=sc.nextInt();
        System.out.println(“Second value is:- “);
        int b=sc.nextInt();
        System.out.println(“Sum of both digits:- “+Add(a, b));
    }
    }

6) Write a program to show largest among three numbers using binary minus operator.

package javaapplication9;
import java.util.Scanner;
public class JavaApplication9 {
    public static void main(String[] args)
    {
        Scanner s = new Scanner(System.in);
        int a = s.nextInt();
        int b = s.nextInt();
        int c = s.nextInt();
        if(a-b>0 && a-c>0)
            System.out.println(“Greatest is a :-“+a);
    else
         if(b-c>0)
             System.out.println(“\nGreatest is b :-“+b);
         else
             System.out.println(“\nGreatest is b :-“+c);
    }
}

7) Write a program to show the largest among three numbers using conditional operator.

package javaapplication9;
import java.util.Scanner;
public class JavaApplication9 {
    public static void main(String[] args)
    {
        Scanner s = new Scanner(System.in);
        int a = s.nextInt();
        int b = s.nextInt();
        int c = s.nextInt();
        int big = a > b ? (a > c ? a : c) : (b > c ? b : c) ;
             System.out.println(“\nGreatest elements is :-“+ big);}}

8) Write a program to show the generic root of any number.

package javaapplication9;
import java.util.Scanner;
public class JavaApplication9 {
    public static void main(String[] args)
    {
        Scanner s = new Scanner(System.in);
        int a = s.nextInt();
        int b=0,c;
        while(a>10){
        b=0;
        while(a>0){
        c=a%10;
        a=a/10;
        b+=c;
        }
        if(b>10)
        a=b;
        else
        break;
    }
System.out.println(“\nSum of the digits in single digit is:-“+b);}}

9) Write a c program to show the prime factor of a given number.

package javaapplication9;
import java.util.Scanner;
public class JavaApplication9 {
    public static void main(String[] args)
    {
        Scanner s = new Scanner(System.in);
        int a = s.nextInt();
        int b=0,c,j,i,isPrime;
       for(i=2; i<=a; i++)
    {
        /* Check ‘i’ for factor of num */
        if(a%i==0)
        {
            /* Check ‘i’ for Prime */
            isPrime = 1;
            for(j=2; j<=i/2; j++)
            {
                if(i%j==0)
                {
                    isPrime = 0;
                    break;
                }
            }
            /* If ‘i’ is Prime number and factor of num */
            if(isPrime==1)
            {
                System.out.println(i);
            }
        }
    }
}
}

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Interview Questions for Electronics / Electrical Core Companies

by Team IM | Jan 25, 2022 | Any Branch, Any Degree, Bangalore, Batch 2020, Batch 2021, Batch 2022, Blog, Branch CIVIL, Branch CSE, Branch ECE, Branch EEE, Branch EN, Branch IT, Branch ME, BTech Job, Companies Recruitment Notifications, Dell, Govt. Jobs, Govt. Jobs Notifications, Internships, Interview Preparation, IT Jobs, MCA Job, Miscellaneous, Pune, Technical

1) Differentiate between abstract class and Interface in Java?

Abstract class and interface both concepts are used to accomplish abstraction in Java. The primary differences between abstract class and Interface are:

The abstract keyword is used to create an abstract class in Java, whereas interface keyword is used to create Interface.
An abstract class can have both abstract and non-abstract methods whereas Interface can only have abstract methods.
As a general class, abstract class also does not support multiple inheritance, whereas an interface supports multiple inheritance.
An abstract class can extend other class and implement interfaces but an interface cannot extend class. It can only extend other interfaces.
An abstract class may or may not have methods with implementations, but Interface cannot have method implementation.

2) What are the static variable and static block?

Static variable: If we use the static keyword with a variable then it is termed as a static variable. Static variables are the part of the class not, the instance. When we declare any static variable, then it creates a copy in memory which is shared between all the objects. Static variables are not thread safe as it is shared between various objects. Static variables are mainly used for memory management.

Syntax:

static variable_name;

Static Block: A block inside a class with the static keyword is called a static block. A static block is executed at the time of class loading and before the execution of the main method. Static block is primarily used for initialization of the static variable. A class can have multiple static blocks, and they execute in the sequence as they appear in the program.

Syntax:

static{
// code to be executed
}

3) What do you understand by TCP/IP?

TCP/IP stands for Transmission Control Protocol/Internet Protocol. It is a suite of protocols TCP and IP, used for the communication over a network. TCP/IP protocols provide some standard rules for communication between two or more computers over the network. The TCP protocol at the transport layer divides a message or data into packets form and then resembled the packets at the destination part. IP protocol at Network layer is responsible for the moving of these packets to the correct destination.

4) Which is the fastest sorting algorithm?

There is no such specific fastest sorting algorithm because it depends on various factors and all the sorting algorithm gives different performances for different input cases. Although among all the sorting algorithm we can consider Quicksort as a fastest algorithm as it shows time complexity of O(n log n) for the best case and average case and O(n^2) for the worst case.

5) What is tunnelling and tunnelling protocols? Explain their applications?

Tunnelling is also known as port forwarding. These are the communication protocols which allow the secure data movement from one network to another network. Tunnelling enables communication from the private network which sent across the public network, and such process is called as encapsulation.

In tunnelling process, data is converted into the form of packets, which travels through the tunnel. As data packets are moving through the tunnel, they got encrypted by the encapsulation process and when these packets reach the correct destination, then these packets are de-encapsulated and de-encrypted, and the packets again converted to the original data.

Main tunnelling protocols are:

PPTP: PPTP stands for the point-to-point tunnelling protocol. PPTP is available for Windows, Linux, and Mac. This protocol keeps data secure even in the public network. It works with the virtual private network which can be accessed by an authorized user.
L2TP: L2TP stands for Layer 2 tunnelling protocol, which supports VPN. It depends on the encryption protocol for the encryption of data which passes through the tunnel.

Application of tunnelling protocols:

Tunnelling is used in cases where high-level security is required for data transmission over the network.
It is helpful for encryption and decryption of data.

6) Explain Polymorphism in Java?

Polymorphism in Java is an important feature of Object Oriented Programming (OOP), which defines a single object with different forms. With the help of polymorphism, one action can be done in various ways.

There are mainly two types of polymorphism in Java:

Run-time polymorphism
Compile-time polymorphism

Run-time polymorphism: Method overriding is used to achieve Runtime polymorphism. It is also called Dynamic polymorphism or Dynamic method dispatch. In Run-time polymorphism, when we call an override method, it is resolved at run-time, hence it is called as run-time polymorphism.

Compile-time polymorphism: Method Overloading is used to achieve the Compile time polymorphism. It is also called as Static polymorphism and when we call the method, it is resolved at compile time only. That’s why it is called as Compile-time polymorphism.

7) What do you understand by Pointer arithmetic in C?

As we know Pointer is a variable which holds the address of another variable and that variable is a numeric value, so any arithmetic operation performed on a pointer is termed as pointer arithmetic. But we can only perform some limited arithmetic operations on the pointer, which are given below:

Increment
Decrement
Addition
Subtraction
Comparison

8) Explain the difference between packet switching and circuit switching?

The Packet switching and circuit switching both are the switching methods which are used to forward the data packets from the sender to receiver destination.

The main differences between the Packet switching and circuit switching are given below:

Packet Switching	Circuit Switching
In packet switching, data is divided into small parts, termed as packets and then these packets are transmitted from source to destination.	In circuit switching a physical path is established between two endpoints for data transmission.
Packet switching is connectionless	Circuit Switching is connection oriented.
Packet switching can be implemented at the network layer of the OSI model.	Circuit switching can be implemented at the physical layer of the OSI model.
It is mainly designed for data and voice communication.	It is basically designed for voice communication.
Congestion occurs at the time of data transfer phase.	Congestion occurs at the time of connection establishment.

9) What do you understand by CDMA?

CDMA is the acronym for Code-division multiple access, is a standard for the wireless digital cellular network. CDMA is a type of multiplexer, where various transmitters can transmit information simultaneously over a single communication channel. CDMA uses spread-spectrum technology and special coding scheme for data transmission. Various protocols, which are used for 2G or 3G wireless communication, refer to CDMA.

10) What do you understand by demodulating a signal?

Demodulation of a signal is a method of extracting the original information of signal from a carrier wave. An electronic circuit which is used for demodulation is called as a demodulator.

11) What do you understand by telecommunications?

Telecommunication refers to the transmission of any signal, data or any type of information by physical or wireless medium over a significant distance. When the exchange of information between the sender and the receiver occurs with the help of technology, then it is known as telecommunication. In telecommunication there is a communication arrangement with a transmitter and a receiver. At any station, a device which combined the transmitter and receiver is termed as a transceiver.

Basic Elements of Telecommunication System:

Transmitter: Which takes the information and convert into the form of a signal
Transmission medium: A medium over which signal travels it may be an optical fibre cable, or free space.
Receiver: Which receives the signal and convert into a usable form.

12) What are the various advantages of GSM?

GSM is an acronym of Global System for Mobile communication. It defines the standard protocols for the second-generation digital cellular network used by mobile devices.

Advantages of GSM:

GSM allows a reliable and efficient way to transfer data. It also allows transferring text and pictures.
GSM provides better security during the conversation. It ensures that only the caller and receiver are in conversation during a call.
GSM provides the worldwide facility of calls and data transfer, but it may cost high on the international level.
GSM cell phone has clear sound quality, as it filters background noise.

13) What are the various applications of DSP?

DSP is termed as Digital Signal Processing. It is a part of signal processing which is used to perform a variety of signal processing. DSP unit analyses and modifies a signal to increase its performance and efficiency.

Various applications of DSP in communication:

DSP is used in audio signal processing.
DSP is used in encoding the waveforms.
DSP is used for Audio compression.
DSP is used for Digital image processing.
DSP is used for speech processing.
DSP is used in RADAR, biomedicine, weather forecasting, and many more applications.

14) What do you understand by commands?

Commands are the specific instructions given by the user to the computer?s operating system, to perform a particular task. We can input these commands using the command line interface provided by the operating system.

15) Why we use Jump statement in C++?

Jump statements are used to disturb the normal flow of program unconditionally. There are three types of Jump statements available in C++.

Break
Continue
goto.

16) What do you understand by MAC address?

MAC address stands for “Media Access Control” Address is a unique identification hardware number, which uniquely identifies each device on a network. The MAC address is a computer’s unique hardware number which can be determined by Ethernet or Wi-Fi card. A MAC address is of 64 or 48 bits, which is expressed in hexadecimal forms separated by colons such as 2AA:EF:EF3E:2A1B.

17) What do you understand by nested loop?

If a loop exists inside another loop, then it is termed as a nested loop. Or a loop within a loop is called a nested loop. When we use a nested loop in our code then control passes to the outer loop, then for first iteration it executes its following loop and other conditions and so on and repeats until the outer loop finishes.

Syntax:

for(int i=0; i<=10; i++)
{
  For (int j=1; j<I; j++)
   {
   // statement to be executed
}
}

18) Why C language is called a procedural language?

A procedural language means a language which follows a procedure of steps and C is called as Procedural language as it follows a specific pattern of top-down for writing code in it. C language gives more priority to the flow of code rather than data. If we do not follow the pattern then it generates the error.

19) What do you understand by JVM?

JVM is termed as Java Virtual Machine, it is a virtual machine which provides a runtime environment to execute a Java application. JVM is a part of JRE (java runtime environment), which compile the code into Java bytecode for computer’s processor.

JVM mainly perform two functions:

It allows the java program to execute on any platform
It manages and optimizes the program memory.

JVM is responsible for performing the following three activities:

Loading the code
Verification and Execution of code
Provide the runtime environment for application

20) What is the size of the void pointer in C language?

The size of the void pointer depends upon on which platform you are executing the code. The void pointer may have a size of 2 bytes for the 16-bit compiler, 4 bytes for the 32-bit compiler, and 8 bytes for the 64-bit compiler. To check the size of the void pointer, we can use the sizeof operator.

21) Which type of motor can be used for a lift?

In previous time DC motors were used for lift, but it might cause a jerk, so the latest elevators or lift are designed with a 3-phase induction motor with variable frequency.

22) What do you understand by modulation?

Modulation is a process of changing some characteristics such as amplitude, phase, or frequency of a carrier signal with respect to message signal. The main information consists by the message signal and career signal is just used to transmit that low energy message signal to a particular distance without any distortion. In the modulation process, only the carrier signal characteristics can be changed, but the original message characteristic will remain the same.

Types of modulation:

Amplitude modulation
Frequency modulation
Phase modulation
Pulse-code modulation

23) What are the various OSI layers and protocols?

The OSI model stands for Open System Interconnection Model. It is a conceptual framework of seven layers which defines the network communication between two systems. The seven different layers perform different tasks using various protocols.

The Layers with their protocols are given below:

Physical layer: This is the lowest layer of the OSI model which is responsible for transmission and reception of raw data between a device and physical media. This layer converts the raw data into 0 and 1?s bit form. The primary technologies used in the physical layer are Ethernet, Cables, and Hubs, etc.
Data Link layer: This layer obtains data from the physical layer. It checks and corrects the errors occurs in the physical layer. Data link layer is responsible for node-to-node data transfer. It converts the bits into the form of frames. This layer includes technologies such as PPP, FDDI, IEEE 802.5/802.2, and HDLC, etc.
Network layer: The network layer is responsible for routing the packets. It moves the packets from source to destination with the source and destination address. The protocols used in this layer are IP (Internet protocol), ICMP, ARP (Address Resolution Protocol), etc.
Transport layer: This layer takes services from Network layer and provides services to the upper layer. This layer offers host-to-host communication services to the upper layers. It provides connection-oriented communication, reliability and flow control of data packets. The main protocols of the transport layer are TCP (Transmission Control Protocol), UDP (User Datagram control Protocol), DCCP (Datagram Congestion Control Protocol), and SCTP (Stream Control Transmission Protocol).
Session layer: This layer maintains proper communication by establishing, managing and terminating sessions between computers. The communication session consists of request and response which occurs between different applications. This layer is responsible for Session Check pointing and recovery. The protocols for session layers are AppleTalk, and Session Control Protocol (SCP).
Presentation layer: This layer is responsible for the delivery and formatting the data to the Application layer as per requirement. This layer transforms the data into the form which application layer accepts. It may use syntax and semantics. Encryption and decryption of data occur at this layer.
Application layer: This is the topmost layer of the OSI model and closest to end user. This layer directly interacts with the software application. This layer allows the end user to use the network resources. The main protocols used at this layer are HTTP (Hypertext Transfer Protocol), FTP (File Transfer Protocol), SMTP (Simple Mail Transfer Protocol), Telnet.

24) How many numbers of output pins microprocessor 8085 contains?

There are 27 output pins in the 8085 microprocessor.

25) Explain Deadlock?

Deadlock is a state where two processes share the same resources and wait for other to complete before proceeding, and hence the complete process hangs. Such condition is termed as deadlock condition. The deadlock condition occurs mainly in concurrency or multitasking programming.

26) What do you understand by threads?

A thread is a lightweight process or, smallest processing unit. A process can have multiple threads in an operating system. The threads are independent of each other and can share their resources such as memory.

27) What are the various types of Antennas?

An antenna is like a transducer which receives the radio waves propagating through space and convert into electric alternating current or vice-versa. The antenna can be of receiver antenna or transmitter antenna.

Following are the various types of antennas:

Log-Periodic Antennas
Wire Antennas
Traveling wave antennas
Microwave antenna
Reflector Antenna
Other antennas

28) What is the need for 5G technology?

The next generation in mobile network technology will be 5G. The 5G technology will take a boom in every area, after the 4G technology. Although the 4G technology is still developing in many countries and also provides a very high speed, but 5G technology will not only gives a very high speed of 1-10Gbps (approx. in the field) but also make easier and real-time experiences of IoT, Virtual reality with minimum energy usage, and many other advanced features.

29) Why we use multiplexers?

A multiplexer is a combinational logic circuit which selects one of the various analog or digital input signals and produces a single output.

The need of Multiplexers:

The multiplexer is used to reduce the number of electrical connections/ wireless channels for transmission of various signals.
It reduces the cost of the system and also increases efficiency.

30) Differentiate between 2G, 3G, and 4G?

The 2G, 3G, and 4G are different generations of mobile networks which shows different strength and speed of data transfer, where G stands for generation. The following are some main differences between 2G, 3G, and 4G mobile technologies.

2G Technology	3G Technology	4G Technology
It refers to second-generation mobile technology.	It refers to third-generation mobile technology.	It refers to fourth-generation mobile technology.
Data transmission speed of 2G technology was upto 64kbps.	Data transmission speed was upto 144kbps – 3Mbps.	Data transmission speed is 100 Mbps- 1 Gbps.

31) What do you understand of Spread-spectrum?

In Communication, spread-spectrum is a technique by which a signal generated with a particular bandwidth, is deliberately varied in frequency domain resulting in a signal with the wider bandwidth. The spread spectrum techniques are useful for the establishment of secure communication, limit the power flux density, and prevent detection.

32) How packets travel through the network?

The information travels through the internet in the form of the packets and travels through the different OSI layers. When we send a message or any information it breaks into the form of packets. These packets are wrapped which contains header and footer, which tells the

information type,
its source address and
destination address

The packets from the same message follow the different routes, and these packets will travel through the internet until they will not reached to their destination. At destination the packets are recreated and unwrapped to find the original information. While travelling the packets through the internet if one path is blocked then the packets follow alternate route. The machine which is receiving the data will identify if any packet is missing and will send a signal to resend the data. This is the complete process by which data travels through the network.

33) Write a program to print Fibonacci series upto n elements?

#include<stdio.h>    
int main()
{
 int n1=0,n2=1,next_term,i,number=10;
 printf(“\n  Series is  %d %d”,n1,n2);      //print 0 and 1    
 for(i=2;i<number;++i)
 {
  next_term=n1+n2;
  printf(” %d”,next_term);
  n1=n2;
  n2=next_term;
 }
  return 0;
 }

Output:

Series is 0 1 1 2 3 5 8 13 21 34

34) Write a program which generates divisor of an integer?

#include <stdio.h>
int main() {
    int i, n=50;
    for(i=1; i<=n;i++){
        if(n%i==0){
            printf(” %d”, i);
        }
    }
    return 0;
}

Output:

1 2 5 10 25 50

35) Why do we use the Bode plot? Explain its Significance?

In electrical engineering, a Bode plot is a graph which shows the frequency response of the LTI system. It consists of two plots:

Bode magnitude plot which express magnitude of the frequency response.
Bode Phase plot which shows the phase shift.

The significance of bode plot is that it shows the gain and phase response of a LTI system for various frequencies.

36) What are the different phases of the compiler?

A compiler operates in various phases. The phases are interrelated operation that takes source program as input and generates the output passing through various phases. There are mainly two compilation phases:

Analysis Phase
Synthesis Phase

The complete compiler has several phases which are given below:

Lexical Analysis
Syntax Analysis
Semantic Analysis
Intermediate Code Generation
Code Optimization
Code Generation

37) Explain the cellular network?

A cellular network is a communication network for mobile phones and wireless network where the last link is wireless. Cellular network provides communication services using large number of base stations, and use limited power where each base station covers a small area. Each small area in cellular network is called as a cell. In cellular network, it re-use the same frequency for another cell which is away from that base station without any interference. By this phenomenon a large geographical area can be covered with a very limited range of frequency. The following are the key points for cellular network:

Cellular network use multiple low power transmitters.
The complete area is divided into small cells.
The adjacent cells are provided with different frequency to stop the interferences.
The cells which are far away from each other are provided the same frequency which re-use the frequency.

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Accenture First & Second Round: Technical Interview Questions

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Accenture First & Second Round: Technical Interview Questions

Java Interview questions:

1) Why is Java called platform independent?

Java is platform independent that means we can execute our code in any operating system either it is mac, Window or Linux. Java is Platform independent because when we write code, then its compiler converts it into bytecode and this bytecode can be executed on any platform (JDK should be installed in that OS).

2) What do you understand by Exception Handling?

Exception handling is a process of handling exceptions occurs during the execution of a program. Due to the occurrence of exception, execution of programs get halted, so it is very important to handle these exceptions so that program can be executed smoothly. We can handle the exceptions by using five keywords: try, catch, throw, throws, and finally.

3) What is checked and unchecked exception?

Checked exception: If the exception occurs or checked at compile time during the execution of a program, it is called as the checked exception. We should handle these exceptions using try-catch block or using throws keyword.
E.g., if someone tries to read a file which is not present then it will throw a checked exception at compile time FileNotFoundException
Unchecked exceptions: If the exception is not checked at compile time and occurred at runtime then this type of exception is called an unchecked exception. This type of exceptions occur due to an error in the logic of the code. If we do not handle this type of exception then also compiler will not give a compilation error.
E.g. ArithmeticException

4) What are the reasons behind the occurrence of an exception?

Following are the reasons behind the occurrence of an exception:

Accessing a file, which does not exist
Dividing a variable by zero
Inserting an element in the array outside the range
If throw statement occurs
Abnormal execution condition captured by JVM

5) What is OOP concept?

OOP stands for Object-Oriented Programming. Object-Oriented Programming is a coding practice which works with objects and class. Java is one of the programming languages which is based on these concepts. The basic OOP concepts are:

Object
Class
Inheritance
Polymorphism
Abstraction
Encapsulation

6) Explain the basic features of OOPs.

Following are the basic features of OOPs:

Object: – An object is a physical entity which has a state and behaviour. It occupies space in memory. It is a sample of a class. Object helps to access the methods and variables in the program.
Class – A Class is “collection of objects.” A class is a logical entity, which does not take any space. A class includes all the data and methods which shows the behaviour of an object.
Inheritance – Inheritance is a process by which one class can have all properties of other class. Inheritance increases the code reusability. There are two terms used
- Child class (Subclass): Class which inherits other class, called as Child class or derived class.
- Parent class (Superclass): A class which got inherited by another class is termed as parent class or Base class.
Polymorphism: – Polymorphism is a method of performing “a single task in different ways.” Polymorphism enables a programmer to use methods or operators in different ways. In Java, we use method overloading and overriding to obtain the polymorphism.
Abstraction: If we show only functionality and hide the explanations or details then this process is called as Abstraction. For achieving the abstraction, we use two ways in Java
- Abstract class
- Interface
Encapsulation: Encapsulation is a process of enclosing the data and code together to form a single unit. It makes the data safer within the code for any modification. For achieving the encapsulation, we can declare the data variables of class as private.

7) Differentiate between class and object.

The class and object both are the features of OOPs concepts. The basic differences between both features are given below:

The Class is a logical entity whereas Object is a physical quantity.
Class does not occupy memory at the time of creation whereas Object occupied space in memory when it is created.
For declaring a class, we use a ‘class’ keyword followed by a class name, whereas we can create the object using the ‘new’ keyword in Java.
A Class is like a factory which generates object and object are the instances of the class.

8) What is encapsulation in Java?

Encapsulation is a process of enclosing the data and code together to form a single unit. The best example to understand the encapsulation is a capsule which contains the medicine in it.

If we declare all the data members of the class as private, then it is called a fully encapsulated class in Java, and then we can use getter and setter method to access it.
One of the examples of the fully encapsulated class is Java Bean class.
Encapsulation keeps its data hide from other class hence it is also called as data-hiding.

Example for encapsulation:

class EncapsulationEg{
    private String empname;
    private int empage;
    private int empid;
    public String getEmpName() //getter method 
    {
        return empname;
    }
    public int getEmpAge()
    {
        return empage;
    }
    public int getEmpId()
    {
        return empid;
    }
    public void setEmpName(String setvalue)  //setter methods 
{
        empname=setvalue;
    }
    public void setEmpAge(int setvalue){
        empage=setvalue;
    }
    public void setEmpId(int setvalue){
        empid=setvalue;
    }
    }
    public class TestEncapsulation{
        public static void main(String args[]){
         EncapsulationEg en= new  EncapsulationEg();
         en.setEmpName(“Alvin”);
        en.setEmpAge(22);
        en.setEmpId(12568);
         System.out.println(“Employee Name: “ +en.getEmpAge());
         System.out.println(“Employee Age: “ +en.getEmpAge());
         System.out.println(“Employee ID: “ +en.getEmpId());
    }
}

Output:

Employee Name: 22
	Employee Age: 22
	Employee ID: 12568

9) What is Recursion and recursive function in Java?

Recursion is a process of calling a method by itself continuously till not get termination point. A method which calls itself is called as a recursive method.

Syntax:

Return-type method_name()
{
// Code to be executed
method_name(); // same name of calling method   }

10) How can you differentiate between C, C++, and Java?

There are the following differences between the C, C++, and Java language.

Index	C language	C++	Java
1.	C language is a procedural language.	C++ is an object-oriented language.	Java is also an object-oriented language (not pure as it also supports primitive data types).
1.	C language is platform dependent.	C++ is platform dependent.	Java is platform independent language.
1.	C language supports pointers.	C++ language also supports pointers.	Java does not support pointers.
1.	We cannot create our own package in C language	In C++ language also, we cannot create our package.	In the Java language, we can create our package and can specify the classes.
1.	In C, there is no any concept of inheritance.	In C++, we can use multiple inheritance.	Java does not support multiple inheritance.

11) What do you understand by runtime polymorphism?

Polymorphism is a method of performing “a single task in different ways.” Polymorphism is of two types

Runtime Polymorphism
Compile-time polymorphism

Here we will discuss runtime polymorphism.

Runtime Polymorphism– We can achieve runtime Polymorphism by method overriding in Java. And method overriding is a process of overriding a method in the subclass which is having the same signature as that of in superclass.

class A{    //Superclass
void name()
{
System.out.println(“this is student of Superclass”);
}
}
class Student extends A  //Subclass
{
void name(){      // method Override with same signature(runtime polymorphism)
System.out.println(“this is student of subclass”);
}
public static void main (String[] args) {
A a= new A();    // refrence of A class
A b= new Student();   // refrence of student class
a.name();
b.name();
}
}

Output:

this is student of Superclass
this is student of subclass

12) How can you differentiate between method overloading and method overriding?

No.	Method overloading	Method overriding
1.	The process of calling two methods having the same name with different parameters is called method overloading (in the same class)	The process of calling two methods, one in the subclass and other in the superclass, having the same signature is called as method overriding.
2.	It can be accessed within a class.	Method overriding requires two classes to be accessed which having IS-A relationship.
3.	Return type may be changed or may remain same with different parameters	Return type should be the same for both methods.
4.	Method overloading is a concept of compile-time polymorphism.	Method overriding is a concept of method overriding.
5.	e.g. class A{ void m1() {// codes…….} Void m1 (int a) {//code………}	e.g. class A { void m1(){ // code…………} } Class B extends A{ Void m1(){ // code………..}

13) What are the keyword “super” and “this” in Java?

super keyword: “super” is a keyword in Java which is used to give reference to the object of parent class. “super” keyword cannot be used as an identifier as it is reserved keyword in Java.

this Keyword: “this” keyword in Java is used to refer to the object of the current class. The ‘this’ keyword cannot be used as an identifier as it is a reserved keyword in Java.

14) What is an interface in Java? Can we implement multiple interfaces in one class?

Interface in Java is a way to achieve the abstraction. The Interface is like a class but not exactly as Interface also can have methods and variable as the class does but Interface only contain method signature does not have the body.

The Interface cannot be instantiated in Java.
The Interface contains methods which are public and abstract (by default).
A class can implement an interface.
For declaring an interface, we use the keyword interface.

Syntax:

interface Interface_Name{
//Methods
}

We can implement multiple interfaces in one class and parent interfaces can be declared using a comma(,) operator.

Syntax:

public class A implements C, D {
Code
}

15) Explain inheritance in Java? How can it be achieved?

Inheritance in Java is a process by which one class can have all properties of other class. That means one class inherits all the behaviour of the other class.
Inheritance increases the code reusability.
Inheritance is an important feature of OOP concept.
Inheritance is also a representation of the IS-A relationship

There are two terms used in inheritance:

Child class (Subclass): Class which inherits other class, called a Child class or derived class.
Parent class (Superclass): A class which got inherited by another class is termed as parent class or Base class.

The Syntax of java inheritance:

Class A extends B     // Here A represents subclass and B represent Superclass
{
// Code 
}

16) Can we use multiple inheritance in Java? Explain with reason?

No, we cannot use multiple inheritance in java as it creates ambiguity and diamond problem in the program. To overcome this problem, we can use interface in Java.

Let suppose class A inherits the two parent class B and C in which a method with the same name is present in both the classes and hence when we try to override that method it will create confusion for the compiler and will give the compilation error. Therefore, Java doesn?t support multiple inheritance.

17) What can we do if we want to access a private member of a class?

We can access private members of the class by using public getters and setters from outside the class in Java.

18) What is the significance of “static” keyword?

Static keyword in Java is a non-access modifier which can be used with the block, variable, methods, and nested classes.
Static Keywords are the part of the class, and it does not belong to the instance of the class.
We use static keyword in java with variables, block, and method for achieving memory management.
Java static property can be shared by all the objects.
For accessing the static members, we don’t need to create the instance of the class.

19) What is “Collection Framework” in Java?

Collection Framework in Java is an architecture for storing the classes, and interfaces and manipulating the data in the form of objects. There are two main interfaces in Collection Framework that are:

Java.util.Collection
Java.util.Map

20) What is List interface in collections?

List interface is an interface in Java Collection Framework. List interface extends the Collection interface.

It is an ordered collection of objects.
It contains duplicate elements.
It also allows random access of elements.

Syntax:

public interface List<E> extends Collection<E>

21) What do you understand by object cloning?

Object cloning is a mechanism of creating the same copy of an object. For object cloning, we can use clone() method of the Object class. The class must implement the java.lang.Clonable interface, whose clone we want to create otherwise it will throw an exception.

Syntax of clone() method:

protected Object clone() throws CloneNotSupportedException

22) Can we insert duplicate values in Set?

We cannot insert duplicate elements in Set. If we add a duplicate element, then the output will only show the unique elements.

23) What is the difference between Collections, and Collection in Java?

Collection and collections both are the part of Java Collection Framework, but the primary differences between both are given below:

A Collection is an interface in java and Collections is a class of collection framework.
The Collection interface provides the methods that can be used for data structure whereas Collections class provides the static methods which can be used for various operation on a collection.

24) What is “Diamond problem” in Java? How can it be removed?

The Diamond problem occurs in multiple inheritance, but Java does not allow multiple inheritance. In case of Java, it can occur with interfaces. When we implement two interfaces which are having methods with the same signature then it creates ambiguity for the compiler, and it gives compile time error. Its structure looks like diamond so it is called as Diamond problem.

E.g. Let’s take an example which will show the diamond problem.

interface InterfaceA {
default public void m1() { System.out.println(“This is interface A!”); }
}
interface InterfaceB {
default public void m1(){ System.out.println(“This is interface B!”); }  //same signature as interface InterfaceA?
}
public class Simple implements InterfaceA, InterfaceB {
public static void main(String args[]) {
Simple s1= new Simple();
s1.m1();   // It will give error..
}}

Error: Simple.java:10: error: class Simple inherits unrelated defaults for m1() from types InterfaceA and InterfaceB

25) What is an abstract class in Java?

An Abstract class is used to achieve abstraction in Java. If we use the keyword “abstract” with the class name, then it is called as an abstract class.
An Abstract class can have only methods without body or can have methods with some implementation.
The Abstract class cannot be instantiated
It’s not necessary that an abstract class should have an abstract method.

Syntax:

abstract class Student{
}

26) What is deadlock condition in multithreading?

A Deadlock condition occurs in the case of multithreading. It is a condition when one thread is waiting for an object lock, which is already acquired by another thread and the second thread is waiting for lock object which is taken by the first thread, so this is called deadlock condition in Java.

27) Differentiate between Collection and array.

The Collection and Array both are responsible for storing the data, but the fundamental differences between both are given below:

Arrays are always of fixed size, we cannot change its size at runtime, but In Collection, size can be changed dynamically.
Arrays can only store homogeneous or similar type objects, but in Collection, both homogeneous and heterogeneous objects can be stored.
Arrays cannot provide the “ready-made” methods for user requirements as sorting, searching, etc. but Collection includes readymade methods to use.
Arrays are good in performance as compare to Collection but Array take more space in memory in comparison to Collection.

C/C++ Interview Questions

28) What is call by value and call by reference?

There are two ways in C language to pass the values in the function that are:

Call by Value
Call by reference

Call by value: In call by value, a copy of the value is passed to the function so, if we change in formal parameters it will not affect the actual parameters. When we change in the value of the formal parameter in the “calling function,” it just takes it as the local variable and does not affect the actual value.

Call by reference: In call by reference, an address of that value is passed to the function so, if we make any changes in formal parameters it will affect the actual parameter as well.

29) Explain dynamic memory and static memory allocation.

There are two types of allocation of memory:

Static memory allocation: The allocation of memory at the starting of the program is called static memory allocation. In static memory allocation size remains fix i.e. we cannot change the size at runtime. Static memory allocation is used in Array.
Dynamic memory allocation: The allocation of memory at runtime is called as dynamic memory allocation. We can specify a size at runtime as per need. The memory gets allocated from heap area, and it can also be deallocated from same. Dynamic memory allocation used in pointers.

30) What is difference between “var++” and “++var”?

The expressions, ( var++)and ( ++var) both are used for the incrementing the value of variable var.

The main difference between both is that, (var++ ) it gives the evaluation of statement first and then it increments the value by one whereas (++var) is used as it increments the value by one before the evaluation of the expression.

E.g.

#include <stdio.h>
int main()
{
int a,b;
a=5, b=1;
printf(“%d %d”, a++, a);   //will generate 5, 6 as output
printf(“%d %d”, ++b, b);    //will generate 2, 2 as output
)

31) Differentiate between class and structure in C++.

The class and structure both are approximately equivalent to each other. But the main differences between both the terms are given below.

The members of the class are accessed as private by default whereas members of the structure are accessed public by default.
Class in C++ is a group of objects, related variables, and functions, whereas Structure is a user-defined data type which performs its operation
We can declare a class using the keyword ‘class’, whereas we can declare a structure using the keyword ‘struct.’
The objects of the class, created at heap area of the memory, whereas the object of the structure created on stack area of memory.

32) What are the access specifiers in C++?

We use access specifier to prevent the access of the class members or to implement the feature of Data Hiding. In C++, there are some keywords used to access specifier within class body, which are given below:

Public: If we specify a class member as public then it will be accessible from anywhere within a program. We can directly access the private member of one class from another class.
Private: If we specify any class member as private then it will only be accessed by the function of that class only. We cannot access the private member of the class outside the class.
Protected: Protected access specifier is mainly used in case of inheritance. If we define the class member as protected, then we cannot access class member outside the class, but we can access it by subclass or derived class of that class.

E.g. Below is the example to show the access specifier in C++.

33) Why we use of “getch()” in a program?

The getch() function is a predefined library function which is used to take a input character from the screen, and it holds the screen till it not get character from input.

#include<stdio.h>
main()
{
printf(“enter the character. \n”);
getch();
}

Output:

enter the character.

34) What does “main()” function in C++? Can we run a program without main method?

In C++ programming language the main() function is the entry point of that program. When we start execution of any program, execution directly goes to the main() in the program.

Syntax for main():

void main(){
///Program body;
}

35) What is the declaration and definition of a variable?

Declaration of Variable: Declaring a variable or function is that we are declaring the name and its type so that it can be used in the program. The Compiler can understand and use those variables and functions. Declaring a member gives its representation in that program.

e.g.

extern int x;
extern char  y;     // It tells the compiler that there are two variables x and y of types char and int

Definition of Variable: Defining a variable means, we are providing some value to it, or we are initializing it with some value. Defining a variable or any member of the program gives the complete information about it.

e.g.

int x= 2;
char y = ‘A’,  ‘B’;    // It defines the variable  x and y by giving its value or body.

36) What do you understand by Friend function?

A friend() function in C++ is a function which can access private and protected members of another class in which it is declared as a friend. We can declare a function as a friend function by using keyword friend. A friend function can be of two types:

Method of another class
A global function

Syntax:

class Class_Name {
//Line of code
friend return-type func_name() ;}

The above-declared friend function can use private members of the class.

37) What is memory allocation in C?

Memory allocation is a process of allocating or reserving some portion of the memory (or as per need) for the execution of the code.

There are mainly two types of memory allocation in C:

Static memory allocation
Dynamic memory allocation

Static memory allocation: The allocation of memory at the starting of the program is called static memory allocation. In static memory allocation size remains fix, i.e., we cannot change the size at runtime. Static memory allocation is used in Array.
Dynamic memory allocation: The allocation of memory at runtime is called as dynamic memory allocation. We can specify a size at runtime as per need. The memory gets allocated from heap area, and it can also be deallocated from same. Dynamic memory allocation used in pointers. There are four types of the predefined function used for dynamic memory allocation
1. malloc()
2. calloc()
3. free()
4. realloc()

38) Differentiate between malloc() and calloc()?

The malloc() and calloc() are the two pre-defined library function available in <stdlib.h> Library. Both the functions are used for dynamic memory allocation for the execution of the program. The basic differences between the malloc() and calloc() are given below:

The malloc() stands for memory allocation while calloc() stands for contiguous allocation
The malloc() allocates a single block of memory whereas calloc() allocates multiple blocks of memory.
The malloc() takes only one argument, i.e., size of given block. Whereas calloc() takes two arguments, i.e., a number of blocks to be allocated and size of all blocks.
The malloc() function is faster than calloc() function for memory allocation.

Syntax for malloc() function:

ptr= (type_cast*) malloc( size_t size );

Syntax for calloc() function:

ptr= (type_cast *) calloc(n , size_t size );

39) Why is C a procedural language?

Procedural language defines a language which follows some pattern, hence C language is called as procedural language as in C language a programmer must follow a specific pattern or flow of the program. C language follows a top-down approach to solve a problem. It mainly focuses on the flow of the program rather than the data.

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60 Wipro important Technical Interview Questions with Answers

by Team IM | Jan 25, 2022 | Any Branch, Any Degree, Bangalore, Batch 2017, Batch 2018, Batch 2019, Batch 2020, Batch 2021, Batch 2022, BCA Job, Blog, Branch CIVIL, Branch CSE, Branch ECE, Branch EEE, Branch EN, Branch IT, Branch ME, BTech Job, Companies Recruitment Notifications, Govt. Jobs, Govt. Jobs Notifications, Internships, Interview Preparation, IT Jobs, MCA Job, Miscellaneous, Pune, Technical, Wipro

Wipro Technical Interview Questions

1) What are the functionalities of an operating system?

These are some major functionalities of an operating system:

The operating system shares the Computer’s memory and sharing of the central processing unit time by various applications and peripheral devices.
An operating system provides a user interface, i.e., graphical user interface and command line.
An operating system includes functionality for booting the computer.
Perform some basic tasks, i.e., managing the peripheral devices.
It provides file management which refers to the way that operating system stores, retrieves, manipulates, and saves data.

2) What is the difference between UNIQUE key and PRIMARY key constraints?

Difference between unique key and primary key constraints:

Unique key	Primary key
A table can contain multiple unique keys.	A table can contain only one primary key.
NULL values are allowed.	NULL values are not allowed.
It helps to maintain a unique data in a column of a table.	It helps to identify a unique row from a table.
For MS SQL server databases, a unique constraint will generate a unique NON-CLUSTERED INDEX	Primary key will generate a unique CLUSTERED INDEX

3) How can you delete the duplicate row in a table?

In case of duplicate rows, you have to be more careful at the time of fetching records from the table.

To overcome this problem, we use a DISTINCT keyword.

It is used along with a SELECT statement to eliminate all duplicate records and fetching unique records.

Syntax:

The basic syntax to eliminate duplicate records from a table is:

SELECT DISTINCT column1, column2,….columnN
FROM table _name
WHERE [conditions]

4) Define the SQL Profiler?

SQL Profiler can be defined as the profiler utility which is mainly used to track connections to the SQL Server and also determine the activities such as which SQL Scripts are running, and which one is getting failed, etc.

5) What is stored procedure? Explain with example.

Stored procedures are a batch of SQL statements that can be executed in a couple of ways. Most of the DBMS support stored procedures; however, not all do. The stored procedure increases the reusability as here the code or the procedure is stored into the system and used again and again that makes the work easy.

Syntax:

CREATE PROCEDURE procedure_name
AS
sql_statement
GO;

To execute a stored procedure

EXEC procedure_name;

Create a table and use this syntax for example.

6) What is a process and what is a thread?

A thread is a lightweight sub-process, the smallest unit of processing. It is a separate path of execution.

Threads are independent that means if there is an exception in one thread, it doesn’t affect other threads. It uses a shared memory area.

The process is heavyweight and can consists of multiple threads. It is a small part of a program.

7) What are the advantages of a thread? How does the multithreading look like?

These are the following advantages of a Thread:

It provides efficient communication.
It minimizes the context switching time.
By using thread, we can get the concurrency within a process.
Thread allows utilization of multiprocessor architectures to a greater scale and efficiency.
A process which executes multiple threads simultaneously is known as multithreading.
A thread is a lightweight sub-process, the smallest unit of processing.

To achieve multitasking in java, we have two ways:

Multiprocessing and multithreading

One process may contain more than one thread and execute simultaneously is known as multi-threading.

8) What are Multi-Processing and Multitasking?

Multitasking: As the name indicates multiple tasks run on a single CPU. We use multitasking to utilize the CPU.

Multitasking can be achieved in two ways:

Process-based Multitasking (Multiprocessing)
Thread-based Multitasking (Multithreading)

Multi-processing: Multi-processing refers to the ability of a system to support more than one central processing unit at the same time.

Multithreading: As the name indicates multiple threads run concurrently.

A thread is a lightweight sub-process, the smallest unit of processing.

9) What are stack and Queue and its applications?

Stack

The stack is an ordered list in which, insertion and deletion can be performed only at one end that is called a top.
The stack is a recursive data structure having a pointer to its top element.
Stacks are sometimes called as Last-In-First-Out (LIFO) lists, i.e., the element which is inserted first in the stack will be deleted last from the stack.

Applications of Stack:

Recursion
Expression evaluations and conversions
Parsing
Browsers
Editors
Tree Traversals

Queue

A queue can be defined as an ordered list which enables insert operations to be performed at one end called REAR and delete operations to be performed at another end called FRONT.
The queue is referred to be as the First-In-First-Out list.
For example, people waiting in line for a rail ticket form a queue.

Applications of Queue:

The queues are widely used as waiting lists for a single shared resource like a printer, disk, CPU.
The queues are used in the asynchronous transfer of data (where data is not being transferred at the same rate between two processes), e.g., Pipes, file IO, sockets.
The queues are used as buffers in most of the applications like MP3 media player, CD player, etc.
The queues are used to maintain the playlist in media players to add and remove the songs from the playlist.
The queues are used in operating systems for handling interrupts.

10) What is indexing, what are the advantages and disadvantages of it?

Indexes are special lookup tables. It is used to retrieve data from the database very fast.

An Index is used to speed up select queries and where clauses. But it shows down the data input with insert and update statements. Without affecting the data, we can create or drop indexes

An index in a database is just like an index in the back of a book.

Indexing can be of the following types

Primary index, secondary index, and clustering index.

The advantages of indexes are as follows:

An index makes it possible to retrieve data quickly.
Index’s use in queries usually results in much better performance.
They can be used for sorting. A post-fetch-sort operation can be eliminated.
Index guarantees uniquely identifiable records in the database.

The disadvantages of indexes are as follows:

Indexes decrease the performance on inserts, updates, and deletes.
Indexes take up space (this increase with the number of fields used and the length of the fields).
Databases will have monocase values in fields that are indexed.

11) What is De-Normalization where does it have?

Denormalization is the process of boosting up database performance and adding of redundant data which helps to get rid of complex data. Denormalization is a part of database optimization technique. This process is used to avoid the use of complex and costly joins.

Denormalization doesn’t refer to the thought of not to normalize instead of that denormalization takes place after normalization. In this process, firstly the redundancy of the data will be removed using normalization process than through denormalization process we will add redundant data as per the requirement so that we can easily avoid the costly joins.

12) What are the Different Objects in DBMS?

A database objects use to store or reference data in the database. Any statement which is written with CREATE Command is known as the database object.

Different types of object in DBMS are:

View: This object is used to create a view in the database. It is a logical table based on another view. A table on which view is based is called the base table.

Table: we can create a table in a database by using the CREATE TABLE statement.

Sequence: This object command used to create a sequence in the database. It is a user-created database object which is shared by multiple users to generate unique integers.

Index: A database object can create indexes in the database by using an index. Indexes are used for fast retrieval of rows from a table.

Synonym: This object is also used for creating indexes in the database. By synonym, you can easily access the objects

13) What are Self-Join and Outer Join, where do you use it?

Self-Join: A self-join is a join which joins the table with itself, means that each row of the table is combined with itself and with every other row of the table. The table contains a FOREIGN KEY which references its PRIMARY KEY.

It shows the one-to-many relationship in a table also known as a unary relationship.

Now come to SQL outer join, all the content of both tables is integrated together either they are matched or not.

An outer join is of two types:

1. Left outer join (also known as left join): this join returns all the rows from left table combine with the matching rows of the right table. If you get no matching in the right table, it returns NULL values.

Syntax: Left outer join

SELECT table1.column1, table2.column2…..
FROM table1
LEFTJOIN table2
ON table1.column_field = table2.column_field;

2. Right outer join (also known as right join): this join returns all the rows from right table are combined with the matching rows of left table .If you get no column matching in the left table .it returns null value.

Basic syntax for right joins:

SELECT table1.column1, table2.column2…..
FROM table1
RIGHT JOIN table2
ON table1.column_field = table2.column_field;

15) Explain some differences between TRUNCATE and DELETE commands with their syntax?

There is a slight difference b/w delete and truncate statement. The DELETE statement only removes the rows from the table based on the condition defined by WHERE clause or remove all the rows from the table when the condition is not specified.

But it does not free the space containing by the table.

16) Define memory management in C.

When you run a program, it loads into your computer memory and starts execution by sending and receiving the instructions from the computer’s processor. When your program needs to run a function, then it loads at another part of the memory till it runs and releases that memory when the task is complete.

Now, talk about the concept of dynamic memory allocation in c language, which enables the C programmer to allocate memory at runtime. Dynamic memory allocation in c language is possible by four functions of stdlib.h header file.

malloc()
calloc()
realloc()
free()

17) What are the steps involved in designing complete software?

To build software, a programmer should have to follow the SDLC.

Software development life cycle is a process of developing new software

There are six steps of SDLC:

Planning: Plan about the scope, approach, functionalities, etc.
Requirement analysis: Gather the required tools, data, and information that are required for the project
Designing: Design a prototype to check the architecture of the project.
Coding: coding as per designing.
Testing: testing is done to check whether the actual result meets the required result.
Maintenance: Updates

18) What is the difference between Abstract classes and interface?

Java interface should be implemented using the keyword “implements”; A Java abstract class should be extended using the keyword “extends.”

An Interface can extend interface only; Abstract class have two properties, it can extend only one java class but implement more than one interface at a time.

19) What is the property of a class?

We can define property in a way that property is a member of a class that provides the access of an object or a class to an attribute. For e.g., Properties include the length of a string, the size of a font, the caption of a window, the name of a customer, and so on.

20) Define precondition and postcondition to a member function.

A pre-condition is a condition that must be true before a method runs for it to work

A post-condition is a condition that must be truly guaranteed after a method is finished.

If all the preconditions of this method are satisfied, then postconditions will also meet for the same method.

No guarantee for behavior if the preconditions not meet.

21) How can you sort the elements of an array in ascending order?

C program to sort the element of an array in ascending order.

#include<stdio.h>
include<conio.h>
void main()
   {
       int i, j, a, m, num[30];
       printf(“Enter the value of N \n”);
       scanf(“%d”, &m);
       printf(“Enter the numbers \n”);
       for (i = 0; i < m; ++i)
           scanf(“%d”, &num[i]);
       for (i = 0; i < m; ++i)
       {
           for (j = i + 1; j < m; ++j)
           {
               if (num[i] > num[j])
               {
                   a =  num[i];
                   num[i] = num[j];
                   num[j] = a;
               }
           }
       }
       printf(“Ascending order of elements \n”);
       for (i = 0; i < m; ++i)
           printf(“%d\n”, num[i]);
   }

22) How can you sort the elements of an array in descending order?

C program to sort the element of an array in descending order.

#include<stdio.h>
include<conio.h>
   void main ()
   {
       int num[30];
       int i, j, a, m;
       printf(“Enter the value of N\n”);
       scanf(“%d”, &m);
       printf(“Enter the numbers \n”);
       for (i = 0; i < m; ++i)
        scanf(“%d”, &num[i]);
       /*  sorting begins … */
       for (i = 0; i < m; ++i)
       {
           for (j = i + 1; j < m; ++j)
           {
               if (num[i] < num[j])
               {
                   a = num[i];
                   num[i] = num[j];
                   num[j] = a;
               }
           }
       }
       printf(“Descending order of the elements \n”);
       for (i = 0; i < m; ++i)
       {
           printf(“%d\n”, num[i]);
       }
   }

23) How is macro execution faster than a function?

Macros can define before the main method or within the main method. Macros are pre-processed that means all the macros are processed before the compilation of the program, and the functions are processed after compilation of the program.

24) Write a program to sort the string by using bubble sort.

Bubble sort: Bubble sort is a technique by which you can print the elements of an array in ascending or descending order. Bubble sort is used to sort string too.

Program to sort the string:

 #include <stdio.h>
#include <string.h>
void main()
{
int num, i, j;
char name[15][20], temp[20];
printf(“\n Sorts the strings of an array using bubble sort :\n”);
printf(“Number of strings :”);
scanf(“%d”, &num);
printf(“Input string %d :\n”, num);
for(i=0;i<=num; i++)
{
fgets(name[i], sizeof name, stdin);
}
for(i=1;i<=num;i++)
for(j=0;j<=num-i;j++)
if(strcmp(name[j],name[j+1])>0)
{
strcpy(temp,name[j]);
strcpy(name[j],name[j+1]);
strcpy(name[j+1],temp);
}
printf(“The strings appears after sorting :\n”);
for(i=0;i<=num;i++)
printf(“%s\n”,name[i]);
}

25) Write code in C to print “hello world” without using a semicolon

 #include<conio.h>
#include<stdio.h>
void main()
{
if(printf(“hello world”))
{
}
}

Output:

hello world

26) Write a program to find factorial of a number.

#include<conio.h>
#include<stdio.h>
Void main()
{
int i, fact=1, num;
clrscr();
printf(“Enter the number for which you want to find factorial\n”);
scanf(“%d”, &num);
for(i=1;i<=num; i++)
{
fact=fact*i;
}
printf(“Factorial of %d is : %d”,num,f);
return 0;
}

27) Write a C program for Fibonacci series.

#include<stdio.h> 
#include<conio.h>   
int main()
{
 int n1=0,n2=1,n3,i,number;
 printf(“Enter the number of elements:”);
 scanf(“%d”,&number);
 printf(“\n%d %d”,n1,n2);  //printing 0 and 1    
 for(i=2;i<number;++i)    //loop starts from 2 because 0 and 1 are already printed    
 {
  n3=n1+n2;
  printf(” %d”,n3);
  n1=n2;
  n2=n3;
 }
  return 0;
 }

28) What is the logic behind reverse of a string in java?

The reverse of a string:

import java.util.*;
class ReverseString
{
public static void main(String parvez[])
{
String original, reverse= ” “;
Scanner in=new scanner(system.in);
System.out.println(“Enter the string: “);
original= in.nextLine();
int length=original.Length();
for(i=length-1;i>=0;i–)
reverse=reverse+original.charAt(i);
System.out.println(“Reversed string: “ +reverse);
}
}

Output:

Enter the string: parvez
Reverse string: zevrap

29) Name the operators that can’t be overloaded.

These are the following operators that can’t be overloaded.

Scope Resolution operator (::)
Pointer-to-member Operator (.*)
Member Access or Dot Operator (.)
Ternary or conditional operator (?:)
Object size Operator (sizeof)
Object type operator (typeid)

30) What is polymorphism?

In an object-oriented programming language, polymorphism is a characteristic which means one name with many forms.

We can say that polymorphism shows different behavior in a different scenario.

There are two types of Polymorphism.

Compile time polymorphism: It is known as method overloading.
Runtime polymorphism: it is also known as method overriding.

31) How is C++ struct different from C++ class?

A struct is a bundle. It is a combination of all related elements that need to work together in a particular context. Such as, the restricted number of arguments context can pass to a function:

If you don’t specify the access modifier, visibility (public, private or protected) of the members will be public in the struct and private in the class.

The visibility by default goes just a little further than members: for inheritance, if you don’t specify anything then the struct will inherit publicly from its base class, while the class will do private inheritance:

32) What is DOM?

DOM stands for Document Object Model. It is a programming API for the HTML and XML documents. DOM provides the logical structure of the document and the way in which a document is accessed and manipulated.

DOM represents a table in the hierarchical form.

33) Specify the characters which can be used as the second character of an identifier, but not as the first character of an identifier?

Any number within the range of 0 to 9 can be taken as the second character of an identifier, but as per restriction, it can’t be treated as the first character on an identifier.

34) What Is The List Interface?

List Interface is the subinterface of Collection. It contains methods to insert and delete elements on an index basis. It is a factory of List-Iterator interface. Lists may contain duplicate items. The List interface includes operations for the following:

Positional Access: Manipulate elements based on their numerical position in the list.
Search: Search for specified objects in the list and return its numerical position.
List Iteration: Extend Iterator semantics to take advantage of the list’s sequential nature.
Range-view: Perform arbitrary range operations on the list.

List Interface declaration

public interface List<E> <strong>extends</strong> Collection<E>

35) What Is The Vector Class?

Vector implements List interface and maintains insertion order. Array list and vector class both are similar but with few differences.

Vector is synchronized: Vector is slow because it is synchronized, i.e., in multithreading environment; it will hold the other threads in runnable or non-runnable state until current thread releases the lock of the object.

Vector is a legacy class

Vector increments 100% means doubles the array size if the total number of elements exceeds than its capacity.

36) What is an Iterator Interface?

An iterator is a Java interface, and it has methods to iterate on elements of collections.

You can create your iterator object by calling iterator() method present in collection interface.

The methods of the interface are:

hasNext(): To know if any other elements left in the collection.
next (): Returns the next element.
remove (): To remove the current element from the collection(better not use that method).

37) What is the major difference between yield () and sleep ()?

Sleep () method in Java has two variants one which takes millisecond as sleeping time while other which takes both millisecond and nanosecond for the sleeping duration.

Yield () method pause all the currently executing thread, and give a chance to execute those threads or processes that need to be run. The current thread will continue to run again if no other thread is available to execute.

38) What Are Wrapped Classes?

Wrapper class in Java provides the mechanism to convert primitive into object and object into primitive. The eight classes of the java.lang package is known as wrapper classes in java.

The list of eight wrapper classes is given below:

Primitive Type	Wrapper class
Boolean	Boolean
Char	Character
Byte	Byte
Short	Short
Int	Integer
Long	Long
Float	Float
Double	Double

39) What is garbage collection? Does it guarantee that a program will not run out of memory?

Garbage collection:

Garbage Collection is a process of reclaiming the unused runtime memory automatically. i.e., it is a way to destroy the unused objects.

To do so, we were using free () function in the C language and delete () in C++. But, in Java, it is performed automatically. So, java provides better memory management.

In some cases, programs use up memory resources faster than they are garbage collected. We can also create objects “without new keyword” in programs that are not subject to garbage collection. That’s why garbage collection doesn’t guarantee that a program will not run out of memory.

40) What is the Name of the immediate superclass of the Applet class?

A panel is the immediate superclass of all Applet class.

The panel allows us to format the string.

A panel must have a specific layout out of FlowLayout, BorderLayout, GridLayout. If a Layout is not specified, then the default will be a FlowLayout.

41) What Is A Native Method?

The native is a keyword applied to a method to show that the method is implemented in Native Code (c, c++) using JNI (Java Native Interface). Hence, it is also known as foreign methods. It acts as an interface between Java Native Interface (JNI) and other programming languages.

It is a modifier that is not applicable to classes and objects. Native method declaration should compulsory ends with “;” because its implementation is already given.

42) What are the collections API?

The Collection in Java is a framework that provides an architecture to store and manipulate the group of objects.

All the operations that you perform on a data such as searching, sorting, insertion, manipulation, deletion, etc. can be achieved by Java Collections.

Java Collection means a single unit of objects. Java Collection framework provides many interfaces (Set, List, Queue, Deque, etc.) and classes (ArrayList, Vector, LinkedList, PriorityQueue, HashSet, LinkedHashSet, TreeSet, etc.)

Collection framework has:

Interfaces and its implementations, i.e., classes
Algorithm

43) List out some modifiers that may be used with an Inner class that is a member of an Outer class?

All the modifiers such as

public
private
abstract
final
protected
strictfp
static
default

44) What is the name of the method of the component class which is used to set the position and size of a component?

setBounds () method is having four coordinates (x, y, width, height) to specifying the position and size of a GUI component .

45) Which Java.util Classes and Interfaces Support Event Handling?

java.awt.event.*; Support event handling.

46) How many number of bits are used to represent a character in Unicode, ASCII, UTF-32, UTF-16, And UTF-8 characters?

Unicode requires 16 bits (2 bytes) to represent a character, ASCII requires 7 or 8 bits, and UTF-8 requires 8, 16 and 18-bit pattern.

UTF=16 requires 16 bits and 32 bits pattern.

UTF-32 requires 32 bits pattern

47) What are the restrictions for the location of a package statement within a source code file?

Restriction for the package:

A package must be appeared in the first line of the program source code, excluding blank lines and comments.

48) What are the major differences between preemptive scheduling and time slicing?

Preemptive scheduling:

Under primitive scheduling, the highest priority task executes until it enters the waiting or dead states or any other higher priority task comes into existence.

Time slicing:

Time slicing: A task executes for a fixed period of time and then reenters again in the pool of ready tasks to execute the remaining task later. The scheduler then determines that which task should execute next, based on priority and other factors.

49) Give the name of three component subclasses that support painting.

The canvas class, the Frame class, and Applet class are the subclasses which support painting.

50) When a Readline () reach at the end of file then what will it return?

Readline() will return a null value when it would reach at the end of the file.

51) What is the name of the immediate superclass of the Dialog class?

The window class is the immediate superclass of Dialog class.

52) Define Order of precedence and Associativity, how are they used?

Order of precedence is used with the operators. When a number of operators are used in an expression, it evaluates with the priority of the operators.

Associativity is used to check whether an expression is evaluated from left-to-right or right-to-left.

Order of precedence example:

(5 > 2 + 5 && 4)

The given expression is equivalent to:

((5 > (2 + 5)) && 4)

The expression (2 + 5) will executes first and the result will be 7
Then after first part of the expression (5 > 7) executes and gives 0 (false) as an output
Finally, (0 && 4) executes and gives 0 (false).

Associativity:

4 * 2 / 4

Here, operators * and / have the same precedence. Both “*” and “/” are left to right associative, i.e., the expression on the left is executed first and moves towards the right.

Thus, the expression above is equivalent to:

((4 * 2) / 4)
i.e., (4 * 2) executes first and the result will be 8 (true)
then, (8 / 4) executes and the final output will be 2 (true)

53) What is the rule for a catch or declare method declarations?

Catch block catches any exception that results from the try block. If a checked exception is thrown within the body of the method, the thrown exception must be caught by the method (with the help of try/catch block) or declare it in its throws clause.

54) What is the top class of the AWT Event Hierarchy?

java.awt.AWTEVENT class is the highest-level class of AWT event hierarchy.

55) When is a thread created and started, what is its initial state?

A thread is created and started with its Initial state called “ready” state where a thread is ready to run.

56) Is it possible to declare an anonymous class which implements an interface and extends a class?

Yes, an anonymous class can extend its superclass or implement an interface but cannot use both simultaneously.

57) Define Synchronization and why is it important?

Synchronization is a process which provides a feature by which access of multiple threads to any shared resource can control.

Hence, Java Synchronization is a better option for restriction. i.e., It allows only one thread to access the shared resource.

The synchronization is mainly used to

To prevent thread interference.
To prevent consistency problem.

58) Is Sizeof a Keyword?

Sizeof is an operator in C++ and a keyword in C, but it is not available in java.

59) What is a priority of task and how is it used in scheduling?

The entire task can’t execute simultaneously so that a scheduler assign priorities to all tasks for its execution. Priorities can be high or low depending on the task’s importance, and the integer values determine it.

Higher priority gets CPU for execution first.

60) Describe the three levels of data abstraction?

Data abstraction in DBMS is a process of hiding irrelevant details from users. Because database systems are made of complex data structures, so it makes accessible the user interaction with the database.

Following are three levels of data abstraction:

Physical level: It is the lowest level of abstraction. It describes how data are stored.

Logical level: It is the next higher level of abstraction. It describes what data are stored in the database and what the relationship among those data is.

View level: It is the highest level of data abstraction. It describes only part of the entire database.

61) What is Hashing technique in the data structure?

Hashing is a faster searching technique. The process of mapping a large amount of data item to a smaller table with the help of a hashing function is called hashing. In other words, hashing is a technique to convert a range of key values into a range of indexes of an array.

In terms of java: Hashing is a way to assign a unique code for any variable or object after applying any function or algorithm on its properties.

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Data Structure Interview Questions And Answers For Freshers

by Team IM | Jan 23, 2022 | Blog, Companies Recruitment Notifications, Interview Preparation, Miscellaneous, Technical

Top 50+ Data Structure interview question and answers that are asked for freshers in the technical interview. These are the top 50+ data structure questions along with efficient answers that you can remember easily.

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1. What is data structure?

Data structure as a methodology that defines, stores, and retrieves data systematically and structurally. Data structure is the process of organizing, storing data in computer that can be used efficiently.

2. Define Linkedlist

A linked list is a sequence of nodes in which each node is connected to the node following it. This forms a chain-like link for data storage.

3. List the areas where data structures are applied?

Data structures are essential in almost every aspect where data is involved. In general, algorithms that involve efficient data structure are applied in the following areas: numerical analysis, operating system, A.I., compiler design, database management, graphics, and statistical analysis, to name a few.

4. Explain the primary advantage of a linked list?

A linked list is an ideal data structure because it can be modified easily. This means that editing a linked list works regardless of how many elements are in the list.

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5. Distinguish linear from a nonlinear data structure.

Linear data structure:

1.The linear data structure is a structure wherein data elements are adjacent to each other.

2. Examples of linear data structure include arrays, linked lists, stacks, and queues.

Nonlinear data structure:

1. A non-linear data structure is a structure wherein each data element can connect to more than two adjacent data elements.

2.Examples of nonlinear data structure include trees and graphs.

6. What is an Algorithm?

Algorithm denote a sequence of steps to solve a particular problem.

7. Define graph?

A graph is one type of data structure that contains a set of ordered pairs. These ordered pairs are also referred to as edges or arcs and are used to connect nodes where data can be stored and retrieved.

8. Explain Criteria for algorithm analysis

Algorithms are analysed based on two factors – space and time. It implies execution time and extra space required on the part of an algorithm.

9. Explain algorithm’s asymptotic analysis?

For any algorithm, there are three different levels of execution time based on mathematical binding:

Representation of the Best Case is done by the symbol Ω(n)
Representation of the Worst-Case is done by the symbol Ο(n)
Representation of the Average Case is done by the symbol Θ(n)

10. Can we apply the Binary search algorithm to a sorted Linked list?

No, we cannot apply the binary search algorithm to a sorted linked list because finding the index of the middle element is difficult.

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11. List some important applications of a Stack?

Balanced parenthesis checker
Redundant braces
Infix to postfix using a stack
Infix to prefix using a stack

12. List the common operations performed on a data structure?

Insertion – Addition of a data item
Deletion – Data item elimination
Traversal – Accessing and printing data items
Search – Find a data item
Sort – Data items arranged in a predefined sequence

13. Differentiate STACK from ARRAY.

Stack follows a LIFO pattern. It means that data access follows a sequence wherein the last data to be stored when the first one to be extracted.

Arrays, on the other hand, do not follow a particular order and instead can be accessed by referring to the indexed element within the array.

14. Are linked lists Linear or Non-linear Data Structures?

Linked lists are considered to be the best of both worlds here. Based on usage, if it is a storage policy, then it can be considered as non-linear. Whereas, if a person is considering it based on retrieval strategies, then it can be considered linear.

15. What are the different approaches to developing algorithms?

There are three commonly used approaches to developing algorithms, which are:

Greedy Approach: Choosing the next best option for finding a solution.

Divide and Conquer: The problem is divided into a minimum possible subproblems and each subproblem is solved independently.

Dynamic Programming: A problem is divided into minimal subproblems, and they are solved together.

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16. Explain the use of stacks?

Stacks uses the LIFO method of addition and retrieval of data items that consume only O(n) time.

If you ever need to access data items in reverse order of their arrival, then you can use stacks.

Stacks are more commonly used in expression parsing, a recursive function call, and depth-first traversal of graphs.

Common operations that you can perform on a stack:

push(): Adding an item to the stack top
pop(): Removing an item from the stack top
peek(): Shows the value of a top item without deleting it
is empty(): Check if you have an empty stack
is full(): Checks if you have a full-stack

17. What is the difference between void and null in Data Structures?

Void is a data type identifier in data structures, while null is considered to be a value with no physical presence. When void is used, it indicates that there is no size while initializing the data structure.

18. What is the use of queues?

As the queue follows the First In First Out method, this data structure can be used for working on data items in the exact sequence of their arrival. Queues are widely used in operating systems for different processes. Breadth-First Traversal of Graphs and Priority Queues are some examples of queues.

19. Mention the parts of a linked list?

A linked list typically has two parts: the head and the tail.

Between the head and tail lie the actual nodes. All these nodes are linked sequentially.

20. What is merge sort?

Merge sort is a method of sorting, which is based on the divide and conquer technique. Here, data entities adjacent to each other are first merged and sorted in every iteration to create sorted lists. These smaller sorted lists are combined at the end to form the completely sorted list.

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21. What are the minimum nodes binary trees can have?

Binary trees can have zero nodes or a minimum of 1 or 2 as well. It can be zero in a case where all of the nodes have a NULL value.

22. List the Operations that can be performed in a queue:

enqueue(): Adding items to the rear end of the queue
dequeue(): Removes an item from the front end of the queue
peek (): Shows the value of the front item without removing it
is empty(): Checks if the stack is empty
is full(): Checks if the stack is full

23. What are doubly linked lists?

Doubly linked lists are a special type of linked list wherein traversal across the data elements can be done in both directions. This is made possible by having two links in every node, one that links to the next node and another one that connects to the previous node.

24. Which data structures are used for BFS and DFS of a graph?

BFS (Breadth-First Search) of a graph uses a queue.

Although DFS (Depth First Search) of a graph makes use of a stack, it can also be implemented using recursion that uses function call stack.

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25. What is an AVL tree?

An AVL tree is a type of binary search tree that is always in a state of partially balanced. The balance is measured as a difference between the heights of the subtrees from the root. This self-balancing tree was known to be the first data structure to be designed as such.

26. Explain Greedy algorithm?

Algorithms following greedy approaches build up solutions step by step. It is mostly used in optimization problems. It makes the optimal choice at each step, to solve the entire problem.

Example: Dijkstra Algo, Prim ‘s Algo, Kruskal.

27. Explain Divide & Conquer algorithm?

Algorithms following the D & C approach works in two steps-Divide & Combine. At First we divide the problem into subparts, solve them individually and then combine the result of all subparts to get a collective solution.

Example: Binary Search, Merge Sort.

28. Explain Dynamic Programming?

DP is used to find the most optimized solution by eliminating the standard recursive calls.

Example: Finding fibonacci series.

29. What is the need of Data Structure?

It tells how data can be stored and accessed in its elementary level. It allows us to manage huge amounts of data efficiently. It provides different techniques for searching and sorting data.

30. Explain the role of malloc(), calloc(), realloc() and free()in dynamic memory allocation.

1. malloc() is one of the functions used for dynamic memory allocation. It takes up single arguments, which denotes the number of bytes to be allocated.

malloc() is faster than calloc().

Syntax : int *p = (int *)malloc(sizeof(int))

2. calloc() is one of the functions used for contiguous dynamic memory allocation. It takes up two arguments, in which the first argument denotes the number of bytes to be allocated, and the second argument denotes size of each block. It initializes allocated memory by 0.

3. The realloc() function is used to resize allocated memory without losing old data.

Syntax: void *realloc(void *p, size_t newsize);

4. free() is used to free the memory block that had been allocated dynamically.

31. List types of Linked List ?

1. Singly LL
2. Doubly LL
3. Circular LL
4. Circular Doubly LL

32. How is a linked list better than an array?

1. Array is static and Linked list is dynamic.

2. Linked list avoids memory wastage

33. What is Stack Overflow & Stack Underflow?

Stack Overflow : Condition when array is full and user requests for another insertion.

Stack Underflow : Condition when array is empty and user requests for deletion operation.

34. What is the condition of Stack Overflow?

top=n-1, where n is the number of elements in stack

35. Give some applications from stack?

1. For data reversal.
2. Evaluating arithmetic operations.
3. To calculate postfix expressions.
4. For parsing.
5. For simulation of recursion.

36. What is the basic condition to check whether a circular queue is full or not?

(rear+1)%size=front

37. Explain the concept of Priority Queue?

Priority queue is the collection of elements such that each element has been assigned a priority i.e order in which elements are deleted or processed. An element of high priority is processed before any element of lower priority.

38. What are the minimum number of queues required to implement priority queue?

2, one for data & one for priority.

39. Explain different types of binary tree?

Full Binary tree : Every node has 0 or 2 children.
Complete Binary tree : All internal nodes have 2 children.
Perfect Binary Tree : All internal nodes have 2 children and leaf node at same level
Skewed tree : Tree that goes in a single direction.
1. Left Skewed tree : Node have only left child not right.
2. Right Skewed tree : Node have only right child not left

40. What is the maximum number of nodes in a binary tree of height ‘h’?

2^(h+1)

41. What is the depth of a binary tree with ‘n’ nodes?

D = log(base 2)(n)+1

42. Explain the game of Tower of Hanoi.

The Tower of Hanoi is a mathematical game or puzzle. It consists of three rods and a number of disks of different sizes, which can slide onto any rod. The puzzle starts with the disks in a neat stack in ascending order of size on one rod, the smallest at the top, thus making a conical shape.

43. Differentiate between B-Tree & B+ Tree?

B-tree is a self-balancing tree data structure that maintains sorted data and allows searches, sequential access, insertions, and deletions in logarithmic time. The B-tree is a generalization of a binary search tree in that a node can have more than two children. In B+ Tree, each node contains keys only(not pairs), and all pointers to data records exist at leaf level only.

44. What are the different operations applied on AVL trees?

1. Left-Left Rotation (LL) : right rotate node p.

2. Left-Right Rotation (LR) : left rotate “parent of p” and right rotate “parent of parent of p (p-parent-parent)”.

3. Right-Right Rotation (RR) : left rotate node p.

4. Right-Left Rotation (RL) : right rotate “parent of p” and left rotate “parent of parent of p (p-parent-parent)”.

where p is the node with violating balance-factor.

45. Define Path & cycle?

Path represents the sequence of adjacent vertices whereas a cycle represents a closed path.

46. What are the different ways to represent a graph?

There are two ways to represent a graph, using Adjacency Matrix and Adjacency List.

47. What are the application areas of Graph data structure?

Circuit Designing.
Computer Networks.
In study of DNA structure of organisms.

48. What is Spanning Tree?

It is a subset of a graph, which has all the vertices covered with the minimum possible number of edges. It does not have cycles and can’t be disconnected.

49. Explain the working of selection sort?

In Selection sort, we select a minimum element from the array and store it in the appropriate position.

Time complexity for selection sort – O(n^2).

50. Explain the working of Insertion Sort?

In this, the leftmost element is considered to be already sorted. From the remaining elements, left most is taken out and is compared to already sorted elements to its left.

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