L&T Technology Services C Developer Interview Questions and Answers

Q1. 1. Singleton patter: private constructor + Static function
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Q2. 2. Convert string to integer.
Ans. 
Convert string to integer in C++.
• Use stoi() function to convert string to integer.

• Include <string> header file.

• stoi() function throws an exception if the string is not a valid integer.

• Use stol() or stoll() for long integers.

• Use atoi() for C-style strings.
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Q3. 3. Write a class to debit, credit and balance check functionalities
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A class for debit, credit and balance check functionalities
• Create a class with member variables for balance

• Add member functions for debit, credit and balance check

• Ensure proper validation and error handling

• Consider using exception handling for errors
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Q4. Explain Abstract design pattern.
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Abstract design pattern is a way to define a blueprint for a group of objects with common characteristics.
• It allows creating objects without specifying their concrete classes.

• It promotes loose coupling between classes.

• It is implemented using abstract classes and interfaces.

• Example: Shape is an abstract class and Circle, Square, Triangle are its concrete subclasses.

• Example: JDBC API uses abstract classes and interfaces ...read more
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Q5. How to add external API to project
Ans. 
To add an external API to a project, you need to first obtain the API documentation and credentials.
• Obtain API documentation and credentials

• Integrate API into project using appropriate libraries or frameworks

• Test API functionality and handle errors appropriately
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Round duration - 60 minutes
Round difficulty - Easy

Technical Interview round with questions on Core C concepts, OS mainly.

Q1. What is the difference between a structure and a union in C++?
Ans. 
Structures in C++ allow for multiple data types to be grouped together, while unions share the same memory space for all members.
• Structures in C++ can hold multiple data types, each with its own memory allocation.

• Unions in C++ share the same memory space for all members, allowing only one member to be active at a time.

• Structures are used when different types of data need to be stored together, while unions are used whe...read more
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Q2. What is dynamic memory allocation in C?
Ans. 
Dynamic memory allocation in C allows for allocating memory at runtime, enabling flexibility in memory usage.
• Dynamic memory allocation is done using functions like malloc(), calloc(), realloc() in C.

• It allows for allocating memory as needed during program execution.

• Dynamic memory allocation helps in managing memory efficiently by allocating and deallocating memory as required.

• Example: int *ptr = (int*)malloc(5 * sizeof...read more
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Q3. What is a zombie process?
Ans. 
A zombie process is a process that has completed execution but still has an entry in the process table.
• Zombie processes occur when a child process finishes execution before the parent process can collect its exit status.

• Zombie processes consume system resources and should be cleaned up by the parent process using wait() or waitpid() system calls.

• Zombie processes can be identified using tools like ps command in Unix/Lin...read more
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Q4. Convert a value from Big Endian format to Little Endian format.
Ans. 
To convert a value from Big Endian to Little Endian format, reverse the order of bytes.
• Iterate through the bytes of the value in reverse order

• Swap the positions of each byte to convert from Big Endian to Little Endian

• Example: Big Endian value 0x12345678 becomes Little Endian value 0x78563412
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Q5. What is IPC?
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IPC stands for Inter-Process Communication, which allows processes to communicate and share data with each other.
• IPC enables processes to exchange data and information with each other.

• Common IPC mechanisms include pipes, message queues, shared memory, and sockets.

• Examples of IPC usage include communication between a parent and child process, or between different processes on a network.
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