1. What is the purpose of std::forward in C++?

2. In an order management system, a final class Order is used to prevent extension. What is the primary advantage of this?

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

4. What is the return type of the main function in C?

5. What is the output of the following ?

#include
void main()
{
int a[5] = { 5, 1, 15, 20, 25 };
int i, j, m;
i = ++a[1];
j = a[1]++;
m = a[i++];
printf("%d, %d, %d", i, j, m);
}

6. What will happen if you access memory beyond the array size in C?

7. What is the key difference between LinkedList and ArrayList?

8. Which of the following statements is incorrect?

9. Which of the following statements about enum in C is true?

10. Which of these classes is not synchronized?

11. What is the use of std::priority_queue?

12. What is the output of this code?

int x = 5;

int &y = x;

y = 10;

std::cout << x;

13. What is the output of the following code?

int x = 10, y = 20;

int z = x > y ? x : y;

std::cout << z;

14. what will be the output of the following program?

#include
int main()
{
int a = 10;
printf("%d", a++ * a++);
return (0);
}

15. Which of these is a marker interface?

16. What happens if you attempt to access an out-of-bounds element in a std::vector using operator[]?

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

18. What will the following code output?
java
class Test {
public static void main(String[] args) {
String str = "hello";
str.concat(" world");
System.out.println(str);
}
}

19. What is the output of this code?

int a = 10;

if (a = 5) {

std::cout << "True"; } else { std::cout << "False"; }

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