Indian Railways Railway Signal Engineer Interview Questions and Answers

Abstract Factory is a creational design pattern that provides an interface for creating families of related objects.

• Abstract Factory is used when we need to create families of related objects without specifying their concrete classes.

• It provides an interface for creating objects of related classes without specifying their concrete classes.

• It encapsulates a group of factories that have a common theme.

• It promotes loose c...read more

Range based map iteration can be done using a for-each loop or iterators.

• Use a for-each loop to iterate over the map elements.

• Alternatively, use iterators to traverse the map.

• The range-based for loop is preferred for its simplicity and readability.

• Example: for(auto const& [key, value] : myMap) { //do something with key and value }

Detached threads are independent threads that run separately from the main thread. Joined threads are threads that wait for the main thread to finish.

• Detached threads are created using pthread_detach() function

• Joined threads are created using pthread_join() function

• Detached threads do not need to be explicitly terminated

• Joined threads must be explicitly terminated using pthread_exit() or return statement

• Detached thread...read more

Static code analysis tools are software programs that analyze source code to find potential issues and improve code quality.

• Static code analysis tools scan code without executing it

• They can detect issues such as security vulnerabilities, coding errors, and performance problems

• Examples of static code analysis tools include SonarQube, ESLint, and Checkstyle

Command to list currently running threads in linux

• Use the 'ps' command with the 'H' option to display threads in a hierarchy

• Use the 'top' command to display threads in real-time

• Use the 'htop' command for an interactive display of threads

No, arithmetic operations cannot be performed on unique pointers.

• Unique pointers are used to manage the lifetime of dynamically allocated objects.

• They cannot be copied or assigned, only moved.

• Arithmetic operations are not defined for pointers, including unique pointers.

Designing Facebook is a complex task involving various components and technologies.

• Identify the core features of Facebook such as user profiles, news feed, messaging, and groups.

• Choose appropriate technologies for each component such as PHP for backend, React for frontend, and MySQL for database.

• Ensure scalability and performance by implementing caching, load balancing, and database sharding.

• Implement security measures...read more