Q1 why and when we have to use Inheritance . Q2 difference between fail safe and fail fast iterator Q3 Real life use Application of Linklist, stack, queue. Q4 Reverse a linklist using Recursion Q5 mega prime number program logic Q6 In this they asked 3questions from my Final year project. Q7 difference between primary and foreign key Q8 stored procedures in sql

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Accepted Answer

Interview questions for Software Engineer position

Inheritance is used to create a new class from an existing class, to reuse code and add new functionality
Fail-safe iterators continue iterating even if there is a concurrent modification, while fail-fast iterators throw a ConcurrentModificationException
Linked lists are used in applications like music playlists, stacks are used in undo/redo functionality, and queues are used in job scheduling
To reverse a linked list using recursion, we need to recursively call the function for the next node and then reverse the links
Mega prime number program logic involves checking if a number is prime and then checking if all its digits are also prime
Primary keys uniquely identify a record in a table, while foreign keys establish a relationship between two tables
Stored procedures in SQL are precompiled SQL statements that can be executed multiple times with different parameters

Accepted Answer

Q1: Why and when do we use Inheritance?

Why: Inheritance allows us to create a new class (derived class) based on an existing class (base class). It promotes code reuse, as the derived class inherits attributes and methods of the base class, avoiding redundancy. It also supports polymorphism, enabling dynamic behavior and cleaner code organization.

When: Use inheritance when there is a hierarchical relationship (an "is-a" relationship). For example, if you have a class Vehicle, a Car can inherit from Vehicle because a car is a type of vehicle.
Q2: Difference between Fail-Safe and Fail-Fast Iterators

Fail-Fast Iterators: Fail immediately if there is any structural modification to the collection during iteration (e.g., ArrayList in Java). They throw a ConcurrentModificationException in such cases.

Fail-Safe Iterators: Do not throw exceptions if the collection is structurally modified during iteration. They work on a cloned copy of the collection rather than the original (e.g., CopyOnWriteArrayList in Java).
Q3: Real-Life Applications of Linked List, Stack, Queue

Linked List: Used in applications like music playlists, where songs are linked one after another, and in image viewers where images are viewed sequentially. It’s also useful in dynamic memory allocation.

Stack: Used in undo mechanisms in software, expression evaluation (like parentheses balancing), and recursive function management in programming.

Queue: Commonly used in ticket booking systems, CPU scheduling, and printer task management where tasks are handled in a first-come, first-served manner.
Q4: Reverse a Linked List using Recursion

Here is a simple recursive function in Python:

class Node:
    def __init__(self, value):
        self.value = value
        self.next = None

def reverse_linked_list(head):
    if head is None or head.next is None:
        return head
    new_head = reverse_linked_list(head.next)
    head.next.next = head
    head.next = None
    return new_head

This function recursively reverses the linked list by reassigning pointers.

Q5: Mega Prime Number Program Logic

A Mega Prime is a prime number where each digit itself is also a prime (2, 3, 5, or 7). To check if a number is Mega Prime:

1. Check if the number itself is prime. 2

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