1. A school management system has a Person class with Student and Teacher subclasses. Which Java feature allows calling overridden methods at runtime?

2. What is the result of this code?

#include

int main() {

int x = 10, y = 20;

std::swap(x, y);

std::cout << x << " " << y; return 0; }

3. What does std::future provide in C++?

4. What is the purpose of the ForkJoinPool class?

5. In a concurrent program, which ExecutorService method will block until all submitted tasks are complete?

6. Which of the following is not a valid reason to use an interface in Java?

7. Which of the following is NOT a valid preprocessor directive?

8. What happens when you try to delete a null pointer in C++?

9. What will happen when this code runs?

#include

class A {

public:

A() { std::cout << "Constructor"; } ~A() { std::cout << "Destructor"; } }; int main() { A obj; return 0; }

10. What will happen with this code?

#include

int main() {

int a = 5 / 0;

printf("%d", a);

return 0;

}

11. What will the following program print?
java
class Test {
public static void main(String[] args) {
int x = 10;
System.out.println(x++ + ++x);
}
}

12. What is the output of the following code?

#include

int main() {

int a = 5;

int *p = &a;

*p = 10;

printf("%d", a);

return 0;

}

13. In an ecommerce system, you want to hide sensitive user details like passwords. Which OOP principle helps achieve this?

14. What does the following code snippet indicate?

void foo() noexcept { }

15. What is the output of this code?

#include

int main() {

int arr[] = {10, 20, 30};

int *ptr = arr;

ptr++;

std::cout << *ptr; return 0; }

16. What is the output of this code?

#include

void display(int x = 10) {

std::cout << x; } int main() { display(); return 0; }

17. What will happen with the following code?

#include

int main() {

char str[5] = "hello";

printf("%s", str);

return 0;

}

18. In an inventory system, you want to restrict access to methods that update product quantities to only admin users. How can you achieve this in Java?

19. What does the following code print?

#include

int main() {

int x = 10;

int y = 5;

printf("%d", x++ + ++y);

return 0;

}

20. What is the purpose of the volatile keyword in C?