Patra Electronics Retail Store Manager Interview Questions and Answers

I had a great stay at IIT Roorkee and spent my time exploring various opportunities and learning new skills.

• I was actively involved in various technical clubs and societies on campus

• I participated in coding competitions and hackathons

• I also took part in organizing technical events and workshops

• Apart from academics, I enjoyed playing sports and exploring the scenic campus

• Overall, my stay at IIT Roorkee was a fulfilling

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.

Functions to create and delete nodes in a stack

• To create a stack, initialize a top pointer to null

• To push a node, create a new node and set its next to the current top, then set top to the new node

• To pop a node, set top to its next and return the popped node

• To delete the stack, pop all nodes until top is null

Code for producer-consumer problem using mutex

• Create a shared buffer with a fixed size

• Create a mutex to control access to the buffer

• Create a semaphore to keep track of the number of items in the buffer

• Create a producer thread that adds items to the buffer

• Create a consumer thread that removes items from the buffer

• Use mutex to lock the buffer while adding or removing items

• Use semaphore to signal when the buffer is full o

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.

• Mute...read more

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

• Exam...read more

Deadlock is a situation where two or more processes are unable to proceed because they are waiting for each other to release resources.

• Prevent deadlock by using a proper resource allocation strategy

• Avoid holding onto resources for too long

• Use timeouts to release resources if they are not being used

• Implement a deadlock detection and recovery mechanism

• Avoid circular wait by imposing a total ordering of all resource types

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

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 la

To find the middle of a linked list, use two pointers - one moving at twice the speed of the other.

• Initialize two pointers - slow and fast

• Move the slow pointer one step at a time and the fast pointer two steps at a time

• When the fast pointer reaches the end of the list, the slow pointer will be at the middle

Time complexity of building a heap using linked list and arrays

• Building a heap using linked list takes O(nlogn) time complexity

• Building a heap using arrays takes O(n) time complexity

• Linked list implementation is slower than array implementation

Yes, static variables can be defined in header files.

• Static variables defined in header files have global scope within the file.

• They can be accessed by any function within the file.

• However, if the header file is included in multiple source files, each file will have its own copy of the static variable.

• This can lead to unexpected behavior if the variable is modified in one file and then accessed in another.

• It is general...read more

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.

Bi-directional linked list allows traversal in both directions, making it useful for certain algorithms.

• Each node in the list has a reference to both the previous and next nodes.

• Insertion and deletion operations are more complex than in a singly linked list.

• Examples of use include implementing a browser's back and forward buttons or a text editor's undo and redo functionality.

OOPs properties and examples with applications

• Encapsulation: bundling of data and methods within a class. Example: Java class. Application: data hiding and security.

• Inheritance: creating a new class from an existing class. Example: subclass. Application: code reusability and extensibility.

• Polymorphism: ability of an object to take on many forms. Example: method overloading. Application: flexibility and modularity.

• Abstr...read more

Pointers and arrays are related concepts in C programming. Pointers hold memory addresses while arrays hold a collection of values.

• Arrays are a collection of values stored in contiguous memory locations.

• Pointers hold the memory address of a variable.

• Arrays can decay into pointers when passed as arguments to functions.

• Pointer arithmetic can be performed on pointers to access memory locations.

• Pointers can be used to dyna

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, buc...read more

Check if a string is palindrome or not

• Reverse the string and compare with original

• Compare first and last characters and move towards center

• Use recursion to check if first and last characters are equal

Operating system uses memory protection to prevent modification of const variables like const int i=5;

• Operating system marks the memory page containing i as read-only

• Any attempt to modify i will result in a segmentation fault

• Compiler may optimize code by replacing i with its value at compile time

Explanation of memory layout in main memory of computer system.

• Main memory is divided into four segments: stack, heap, data, and code.

• Stack stores local variables and function calls.

• Heap stores dynamically allocated memory.

• Data stores global and static variables.

• Code stores the program instructions.

• Example: int x; //stored in data segment, int *p = new int; //stored in heap segment

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...read more

new() is an operator in C++ used for dynamic memory allocation.

• new() returns a pointer to the allocated memory.

• It can be used to allocate memory for primitive data types, arrays, and objects.

• Memory allocated using new() must be deallocated using delete operator.

• Example: int *ptr = new int;

• Example: int *arr = new int[10];

• Example: MyClass *obj = new MyClass();

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

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.

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.

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

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.

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 ...read more

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 struc...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.

Windows is a proprietary operating system developed by Microsoft.

• Windows is a graphical user interface (GUI) based operating system.

• It is designed to run on personal computers, servers, and mobile devices.

• Windows has different versions such as Windows 10, Windows 8, Windows 7, etc.

• It supports a wide range of software applications and hardware devices.

• Windows is known for its ease of use and user-friendly interface.

UNIX is an operating system developed in the 1970s, while LINUX is a free and open-source operating system based on UNIX.

• UNIX is proprietary, while LINUX is open-source

• UNIX is older and has a longer history, while LINUX is a newer development

• UNIX is more stable and reliable, while LINUX is more customizable and flexible

• UNIX has a more limited user base, while LINUX has a larger and more active community

• Examples of UNIX...read more

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, an

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 - eac...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.

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 Li...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...read more