400+ Interview Questions and Answers

To gather NFR from an unaware client for a new application, follow these steps:

• Explain the importance of performance testing and its benefits

• Provide examples of how performance issues can impact the application and business

• Ask the client about their expectations for the application's performance

• Discuss the application's usage scenarios and expected user load

• Collaborate with the development team to identify potential performance bottlenecks

• Use industry standards and best pract...read more

Two methods to allocate memory in C are malloc and calloc. Malloc allocates memory block of given size while calloc initializes the allocated memory block to zero.

• Malloc allocates memory block of given size while calloc initializes the allocated memory block to zero.

• Malloc returns a pointer to the first byte of allocated memory block while calloc returns a pointer to the first byte of initialized memory block.

• Malloc is faster than calloc as it does not initialize the memory b...read more

There are 6 types of CPU scheduling: FCFS, SJF, SRTF, Priority, Round Robin, and Multilevel Queue. Each has its own advantages and disadvantages.

• FCFS (First-Come-First-Serve) - processes are executed in the order they arrive

• SJF (Shortest-Job-First) - shortest job is executed first

• SRTF (Shortest-Remaining-Time-First) - preemptive version of SJF

• Priority - processes with higher priority are executed first

• Round Robin - each process is given a time slice to execute, then moved to ...read more

Cannot modify value pointed by p, but can change the address it points to.

• p is a pointer to a constant integer with value 5

• a) is valid as p can point to a non-constant integer

• b) is invalid as *p is a constant and cannot be modified

CMOS is a type of semiconductor technology used in digital circuits.

• CMOS stands for Complementary Metal-Oxide-Semiconductor.

• It uses both p-type and n-type MOSFETs to achieve low power consumption and high noise immunity.

• Advantages include low power consumption, high noise immunity, and compatibility with digital circuits.

• Disadvantages include higher cost and lower speed compared to other technologies.

• BJT (Bipolar Junction Transistor) is an alternative technology that is faste...read more

To work with dynamic data, remove duplicates and fix errors, use data cleaning techniques.

• Use software tools like OpenRefine or Excel to clean data

• Identify and remove duplicate data using unique identifiers

• Fix errors by standardizing data formats and using regular expressions

• Use data validation to ensure accuracy and completeness

• Create a data cleaning plan and document all changes made

• Test the cleaned data to ensure it meets the desired quality standards

Program to check if a knight on a chessboard can reach another location in <= given moves

• Create a function that takes the starting and ending positions of the knight and the maximum number of moves allowed

• Use a breadth-first search algorithm to explore all possible moves of the knight within the given number of moves

• If the ending position is reached within the given number of moves, return true, else return false

Thread dumps are analyzed to identify performance bottlenecks and deadlocks in the application.

• To identify the root cause of performance issues

• To identify deadlocks and thread contention issues

• To identify long running threads and blocked threads

• To identify memory leaks and excessive CPU usage

• To identify issues related to garbage collection

• To identify issues related to database connections and transactions

At least 10 rats are needed to figure out which bottle contains poison in an hour.

• Number the bottles from 1 to 1000.

• Use binary representation of the bottle numbers to assign each rat a unique combination of bottles to drink.

• For example, Rat 1 drinks from all bottles with a binary representation that has a 1 in the least significant bit (LSB).

• After an hour, the rats that die will indicate the binary representation of the poisoned bottle.

• By decoding the binary representation, t...read more

C program to reverse a string in-place

• Use two pointers, one at the beginning and one at the end of the string

• Swap the characters at the two pointers and move the pointers towards each other until they meet

• Handle odd-length strings by leaving the middle character in place

Yes, virtual users can be reinitialized if they go to error state with consumable data.

• Reinitializing virtual users can help in identifying the root cause of the error.

• It is important to ensure that the consumable data is backed up before reinitializing the virtual users.

• Reinitializing virtual users should be done only after analyzing the error and identifying the cause.

• It is important to have a backup plan in case reinitializing the virtual users does not resolve the error.

Context switching and parsing are database operations that impact DB server performance.

• Context switching is the process of switching between different tasks or threads in a CPU.

• Parsing is the process of analyzing and interpreting data in a database.

• Both operations require CPU resources and can cause delays in processing other tasks.

• Context switching can be reduced by optimizing code and minimizing the number of threads.

• Parsing can be improved by using efficient algorithms an...read more

malloc and new are used to allocate memory dynamically. Malloc is faster but new is safer.

• malloc is a C function while new is a C++ operator

• malloc only allocates memory while new also initializes the memory

• new throws an exception if allocation fails while malloc returns NULL

• malloc is faster because it does not involve constructor calls

• new is safer because it ensures type safety and prevents memory leaks

Variables accessible from f1.c and f2.c in f3.c. 'a' needs to be declared as extern to be accessed.

• Variables declared as static in f2.c can only be accessed within f2.c

• Variables declared in f1.c can be accessed in f3.c by declaring them as extern

• Variables declared in f3.c cannot be accessed in f1.c or f2.c

Structure and union are data structures in C language. Union stores only one value at a time while structure stores multiple values.

• Structure is used to store different data types while union is used to store only one data type at a time.

• Structure allocates memory for all its members while union allocates memory for only the largest member.

• Structure is used when we want to store multiple values of different data types while union is used when we want to store only one value a...read more

To check if a linked list is circular, we can use Floyd's cycle-finding algorithm.

• Floyd's cycle-finding algorithm uses two pointers, one moving at twice the speed of the other.

• If the linked list is circular, the fast pointer will eventually catch up to the slow pointer.

• If the linked list is not circular, the fast pointer will reach the end of the list and the algorithm will terminate.

Structure byte padding is the insertion of unused bytes between structure members to align them in memory.

• Padding is added to ensure that each member of a structure is aligned on a memory boundary that is a multiple of its size.

• The amount of padding added depends on the size and alignment requirements of the members.

• Padding can affect the size of a structure and the performance of code that uses it.

• For example, a structure with a 4-byte member followed by a 1-byte member will...read more

The priority of a mobile application depends on the business goals and user needs.

• The priority of a mobile application can vary depending on the business goals and user needs.

• For example, a mobile banking app may have a higher priority than a social media app for a bank.

• On the other hand, a social media app may have a higher priority for a media company.

• The priority can also depend on the target audience and the market demand.

• It is important to prioritize features and functio...read more

Storage classes in C define the scope and lifetime of variables.

• There are four storage classes in C: auto, register, static, and extern.

• Auto variables are local to a block and have automatic storage duration.

• Register variables are stored in CPU registers for faster access.

• Static variables have a lifetime throughout the program and are initialized only once.

• Extern variables are declared outside any function and can be accessed by any function in the program.

FPGA stands for Field Programmable Gate Array. It is a type of integrated circuit that can be programmed after manufacturing.

• FPGAs offer flexibility and can be reprogrammed for different applications

• They can be used to accelerate certain tasks such as image processing or cryptography

• FPGAs can be more power-efficient than traditional CPUs for certain applications

• Examples of FPGA manufacturers include Xilinx and Intel (formerly Altera)

Self referential structure is a structure that contains a pointer to the same type of structure.

• It allows a structure to reference itself within its own definition.

• It is commonly used in linked lists, trees, and graphs.

• Example: struct Node { int data; struct Node *next; };

• Here, the Node structure contains a pointer to another Node structure.

To set process priority in Windows and Linux, use task manager and nice command respectively.

• In Windows, open task manager, right-click on the process and select 'Set Priority'

• In Linux, use the 'nice' command followed by the process name or ID and the priority level (values range from -20 to 19)

• Higher priority levels mean the process will get more CPU time

• Examples: 'nice -n 10 firefox' sets Firefox priority to 10 in Linux, 'Set Priority' in task manager allows setting priorit...read more

Use jigsaw puzzle approach to reconstruct the paper.

• Sort the pieces by edges and corners.

• Identify patterns and colors to match adjacent pieces.

• Use trial and error method to fit the pieces together.

• Check for completeness and accuracy of the final paper.

• Use computer vision and machine learning algorithms for automation.

Generating heap dump and thread dump on Unix/Linux systems

• For heap dump: use jmap command with -dump option

• For thread dump: use jstack command

• Heap dump can also be generated using kill -3

• Thread dump can also be generated using kill -QUIT

Thread states in thread dump include NEW, RUNNABLE, BLOCKED, WAITING, TIMED_WAITING, and TERMINATED.

• NEW: thread has been created but not yet started

• RUNNABLE: thread is executing or ready to execute

• BLOCKED: thread is blocked waiting for a monitor lock

• WAITING: thread is waiting indefinitely for another thread to perform a particular action

• TIMED_WAITING: thread is waiting for another thread to perform a particular action for a specified period of time

• TERMINATED: thread has compl...read more

++x is faster than x++ because it increments the value before using it.

• ++x increments the value before using it, while x++ increments the value after using it.

• ++x is faster because it saves the overhead of creating a temporary variable.

• In some cases, the difference in speed may be negligible and the choice between the two may depend on readability and coding standards.

The two statements are equivalent and declare a pointer to a constant integer.

• Both statements declare a pointer to an integer that cannot be modified through the pointer.

• The 'const' keyword can be placed before or after the 'int' keyword.

• The pointer itself can still be modified to point to a different integer.

• Example: const int *p; and int const *p; both declare a pointer to a constant integer.

Feedback in amplifiers is a process of returning a portion of the output signal back to the input.

• Feedback helps to improve the performance of amplifiers by reducing distortion and increasing stability.

• There are two types of feedback: positive and negative.

• Positive feedback increases the gain of the amplifier, while negative feedback decreases the gain.

• Negative feedback is commonly used in amplifiers to improve linearity and reduce distortion.

• Positive feedback is used in osci...read more

The current equation of a MOS transistor describes its behavior in both saturation and linear regions.

• The current equation in saturation region is given by Ids = 0.5 * k * (Vgs - Vth)^2

• The current equation in linear region is given by Ids = k * ((Vgs - Vth) * Vds - 0.5 * Vds^2)

• Ids represents the drain current, Vgs is the gate-to-source voltage, Vth is the threshold voltage, Vds is the drain-to-source voltage, and k is a constant

• In saturation region, the drain current is quadr...read more

Virtual memory is still needed even with large physical memory. Paging helps manage memory efficiently.

• Virtual memory allows for larger programs to run than physical memory can handle

• Paging helps manage memory efficiently by swapping out unused pages to disk

• Virtual memory also allows for memory protection and sharing between processes

• Examples of programs that require virtual memory include video editing software and large databases

Virtual functions are functions that can be overridden in derived classes. Virtual function table stores the addresses of these functions.

• Virtual functions allow polymorphism and dynamic binding

• Virtual function table is a lookup table of function pointers

• Virtual pointer points to the virtual function table

• Size of virtual pointer depends on the architecture of the system

Program to insert a node in linked list

• Create a new node with the given data

• Set the next pointer of the new node to the next pointer of the previous node

• Set the next pointer of the previous node to the new node

Count the number of '-' characters in a string and return 1 if it matches the given number, else return 0.

• Use a loop to iterate through each character in the string and count the number of '-' characters.

• Compare the count with the given number and return 1 if they match, else return 0.

• Handle edge cases such as empty string or negative number input.

Mutex and Semaphore are synchronization primitives used in multi-threaded environments.

• Mutex is used to provide mutual exclusion to a shared resource, allowing only one thread to access it at a time.

• Semaphore is used to control access to a shared resource, allowing multiple threads to access it at a time.

• Mutex is binary, meaning it has only two states - locked and unlocked, while Semaphore can have multiple states.

• Mutex is typically faster and simpler to use than Semaphore.

• We...read more

No, there is no ideal CPU scheduling possible.

• CPU scheduling is a complex problem with many variables.

• Different scheduling algorithms are suited for different scenarios.

• The ideal scheduling algorithm would depend on the specific system and workload.

• For example, a real-time system would require a different scheduling algorithm than a batch processing system.

extern and static are storage classes in C programming language.

• extern is used to declare a variable or function that is defined in another file or module.

• static is used to declare a variable or function that is local to a file or module.

• Example of extern: extern int count; //declares count variable defined in another file.

• Example of static: static int count = 0; //declares count variable local to the file.

Program to find loop in linked list

• Use two pointers, slow and fast, to traverse the linked list

• If there is a loop, the fast pointer will eventually catch up to the slow pointer

• To find the start of the loop, reset the slow pointer to the head and move both pointers at the same pace

Semaphore, mutex, message queues are inter-process communication mechanisms. Semaphores and mutexes are used for synchronization.

• Semaphore is a signaling mechanism used to control access to a shared resource.

• Mutex is a locking mechanism used to ensure mutual exclusion of shared resources.

• Message queues are used for exchanging messages between processes.

• Other types of inter-process communication include pipes, sockets, and shared memory.

• Semaphores and mutexes are used for sync...read more

Stacks can be implemented using two queues, while queues can be implemented using two stacks.

• To implement a stack using queues, we can use one queue for storing elements and another temporary queue for operations.

• To push an element onto the stack, we enqueue it to the temporary queue, then enqueue all elements from the main queue to the temporary queue, and finally swap the names of the two queues.

• To pop an element from the stack, we dequeue an element from the main queue.

• To ...read more

Two things required in Sales are communication skills and product knowledge.

• Effective communication skills to understand customer needs and persuade them to buy

• In-depth knowledge of the product or service being sold to answer customer questions and provide solutions

It depends on the specific use case and input size.

• For small input sizes, simple algorithms like insertion sort or selection sort may be sufficient.

• For larger input sizes, more complex algorithms like merge sort or quicksort may be more efficient.

• For nearly sorted input, insertion sort may be the fastest.

• For input with many duplicates, counting sort or radix sort may be the best choice.

• For input with a known range, bucket sort may be the most efficient.

• Overall, there is no on...read more

A null object is an object that does not have a value or reference to any object.

• A null object is different from an object with a value of zero or an empty string.

• It is often used to represent the absence of an object or value.

• Null objects can be used to avoid null pointer exceptions in programming.

• It is a conceptual idea in programming and computer science.

Which software are you referring to?

• Please specify the software you are asking about

• Without context, it is impossible to answer this question

Virtual functions are functions that can be overridden by derived classes.

• Virtual functions are declared in a base class and can be overridden in a derived class.

• They allow for polymorphism, where a derived class can be treated as its base class.

• Virtual functions are called based on the actual object type, not the pointer or reference type.

• They are declared using the 'virtual' keyword in the base class and optionally overridden using the 'override' keyword in the derived clas...read more

The 'friend' access specifier in C++ allows a non-member function or class to access private and protected members of a class.

• The 'friend' keyword is used to declare a function or class as a friend of a class.

• A friend function can access private and protected members of the class it is declared as a friend of.

• A friend class can access private and protected members of the class it is declared as a friend of.

• The 'friend' keyword does not affect the access specifiers of the clas...read more

Answering questions related to bfs, copy constructor, Kubernetes, Docker, Socket, TCP/UP

• BFS stands for Breadth First Search, a graph traversal algorithm

• Copy constructor is a special constructor that creates a new object as a copy of an existing object

• Kubernetes is an open-source container orchestration platform

• Docker is a platform for developing, shipping, and running applications in containers

• Socket is a software endpoint that establishes a bidirectional communication link b...read more

I have used various tools for DB server tuning such as SQL Profiler, SQL Server Management Studio, and Database Engine Tuning Advisor.

• SQL Profiler for monitoring and analyzing SQL Server activity

• SQL Server Management Studio for managing and configuring SQL Server instances

• Database Engine Tuning Advisor for analyzing workload and recommending index and partitioning strategies

The value of variable 'a' will be incremented by 1.

• The variable 'a' is initialized with value 5.

• A pointer 'p' is created and assigned the address of 'a'.

• The value pointed by 'p' is incremented by 1 using prefix increment operator.

• The final value of 'a' will be 6.

To initialize static variable a in class A, use static A::int a = 0;

• Use the class name followed by the scope resolution operator(::)

• Assign the value to the static variable

• Initialization should be done outside the class definition

Virtual addressing is a memory management technique that allows a process to use a range of memory addresses independent of physical memory.

• Virtual addresses are mapped to physical addresses by the memory management unit (MMU)

• Virtual addresses are allocated to a process during its execution

• Virtual addressing allows for efficient use of physical memory by allowing multiple processes to share the same physical memory

• Examples of virtual addressing include paging and segmentation

Web service is a software system designed to support interoperable machine-to-machine interaction over a network.

• Types of web services: SOAP, REST, XML-RPC, JSON-RPC

• Advantages: interoperability, platform independence, reusability, scalability

• Disadvantages: security concerns, performance issues, complexity

• Example: Amazon Web Services (AWS), Google Cloud Platform (GCP), Microsoft Azure

Code for Fibonacci series nth term and implement strcat, strlen, strcpy without using predefined functions.

• For Fibonacci series, use a loop to calculate the nth term by adding the previous two terms.

• For strcat, use a loop to append the second string to the end of the first string.

• For strlen, use a loop to count the number of characters in the string.

• For strcpy, use a loop to copy each character from the source string to the destination string.

Yes, constant and volatile can be used together.

• Constant variables are read-only and cannot be modified.

• Volatile variables are used to indicate that the value may change unexpectedly.

• Using both together can be useful in multi-threaded environments.

• For example, a constant pointer to a volatile variable can be used to ensure thread safety.

Threads provide concurrency but can lead to deadlocks.

• Advantage: Allows for concurrent execution of multiple tasks.

• Disadvantage: Can lead to deadlocks where two or more threads are blocked and unable to proceed.

• Example: A web server handling multiple requests concurrently using threads.

• Example: A program with multiple threads accessing shared resources without proper synchronization.

• Example: A program with multiple threads waiting for each other to release a resource, causing...read more

Ram is a common name in India and can refer to many people. It is not possible to determine the full name of Ram without additional context.

• Ram is a common first name in India

• There are many people with the first name Ram, so the full name would depend on the individual

• Some common full names for Ram include Ramakrishna, Ramachandra, and Ramakant

Formula is a mathematical expression while function is a pre-built formula that performs a specific task.

• Formula is a combination of mathematical operators and values used to calculate a result.

• Function is a pre-built formula that performs a specific task, such as finding the average of a range of numbers.

• Formulas can be customized and modified, while functions are fixed and cannot be changed.

• Examples of functions include SUM, AVERAGE, MAX, MIN, etc.

A real-time operating system is an OS that processes data and events as they occur, without delay.

• Real-time operating systems are used in applications that require immediate response, such as aviation, medical equipment, and industrial control systems.

• They prioritize tasks based on their urgency and importance, and can handle multiple tasks simultaneously.

• Examples of real-time operating systems include VxWorks, QNX, and FreeRTOS.

Program to find the only duplicate in an array

• Create a hash set to store elements as they are encountered

• If an element is already in the hash set, it is a duplicate

• Return the duplicate element