Standard Template Library (STL) – MCQs

1. : What does STL in C++ stand for?
(A) Standard Transfer Library
(B) Standard Template Library
(C) Structured Type Library
(D) System Template Library

2. : Which of the following is not a type of STL container?
(A) Sequence
(B) Associative
(C) Adapter
(D) Stream

3. : What is the main advantage of using STL?
(A) Code reusability
(B) Portability
(C) Performance optimization
(D) All of the above

4. : Which container stores elements in a linear fashion?
(A) map
(B) set
(C) vector
(D) multimap

5. : Which container allows duplicate elements?
(A) set
(B) multiset
(C) map
(D) unordered_set

6. : Which associative container stores key-value pairs?
(A) vector
(B) list
(C) map
(D) queue

7. : Which of the following is not an STL algorithm?
(A) sort
(B) reverse
(C) add
(D) find

8. : Which container adapter gives LIFO behavior?
(A) queue
(B) deque
(C) stack
(D) vector

9. : Which header file includes STL components?
10. : Which of the following is not a sequence container?
(A) vector
(B) deque
(C) list
(D) map

11. : What does the iterator do in STL?
(A) Stores data
(B) Performs computation
(C) Traverses elements
(D) Removes elements

12. : Which of these containers maintains a sorted order by default?
(A) unordered_map
(B) set
(C) list
(D) stack

13. : Which adapter container uses two ends for insertion and deletion?
(A) stack
(B) queue
(C) priority_queue
(D) deque

14. : What does begin() function return in STL containers?
(A) End iterator
(B) Null pointer
(C) Iterator to first element
(D) Iterator to last element

15. : What does end() function return?
(A) Iterator past the last element
(B) Null
(C) Last element
(D) First element

16. : Which container uses key-value pairs and does not allow duplicate keys?
(A) multimap
(B) map
(C) multiset
(D) vector

17. : Which container allows random access to elements?
(A) list
(B) map
(C) vector
(D) set

18. : What type of container is priority_queue?
(A) Sequence
(B) Adapter
(C) Associative
(D) Hybrid

19. : Which algorithm is used to arrange elements in ascending order?
(A) sort
(B) reverse
(C) rotate
(D) remove

20. : Which function removes all elements from a container?
(A) remove()
(B) erase()
(C) clear()
(D) delete()

21. : Which container does not allow duplicate values?
(A) multiset
(B) vector
(C) set
(D) multimap

22. : What is the use of count() function in STL?
(A) To count elements in a container
(B) To count specific elements
(C) To check if container is empty
(D) To assign a value

23. : What is the time complexity of accessing an element in vector by index?
(A) O(log n)
(B) O(n)
(C) O(1)
(D) O(n log n)

24. : Which container is best for fast search, insert, and delete operations?
(A) list
(B) vector
(C) set
(D) stack

25. : Which algorithm finds the maximum element?
(A) max_element
(B) max
(C) maximum
(D) top

26. : Which container supports insertion/removal at both ends efficiently?
(A) deque
(B) vector
(C) list
(D) map

27. : What does unique() do in STL?
(A) Finds unique elements
(B) Removes consecutive duplicates
(C) Sorts elements
(D) Removes all duplicates

28. : In STL, what is emplace_back() used for?
(A) Inserts at the front
(B) Removes from back
(C) Constructs in place at the end
(D) Sorts the container

29. : What type of iterator is used with set?
(A) Random access iterator
(B) Bidirectional iterator
(C) Input iterator
(D) Output iterator

30. : Which container allows reverse iteration?
(A) vector
(B) set
(C) list
(D) All of the above