One-dimensional and multi-dimensional arrays — C++ MCQs

1. What is a one-dimensional array in C++?
(A) An array of arrays
(B) A variable holding multiple data types
(C) An array stored in heap only
(D) A linear list of elements stored in contiguous memory

2. How do you declare an array of 5 integers in C++?
(A) int arr(5);
(B) int arr[5];
(C) int arr{5};
(D) int arr = 5;

3. What is the index of the first element in a C++ array?
(A) 1
(B) 1
(C) 0
(D) Depends on compiler

4. How do you access the 3rd element of an array named arr?
(A) arr(2)
(B) arr[2]
(C) arr[3]
(D) arr{3}

5. Which of the following is correct initialization of a one-dimensional array?
(A) int arr[5] = {1, 2, 3, 4, 5};
(B) int arr[5] = (1, 2, 3, 4, 5);
(C) int arr[5] = [1, 2, 3, 4, 5];
(D) int arr[5] = <1, 2, 3, 4, 5>;

6. What will be the output of this code?
int arr[3] = {5, 10, 15};
cout << arr[1];
(A) 5
(B) 10
(C) 15
(D) Error

7. What is a two-dimensional array?
(A) An array of integers
(B) A single variable with multiple values
(C) A dynamically allocated array
(D) An array of arrays

8. How do you declare a 2×3 integer array?
(A) int arr[2][3];
(B) int arr[3][2];
(C) int arr(2,3);
(D) int arr{2,3};

9. How do you access the element at 2nd row and 3rd column of arr?
(A) arr[2][3]
(B) arr[1][2]
(C) arr[3][2]
(D) arr(1,2)

10. What is the output?
int arr[2][2] = {{1,2},{3,4}};
cout << arr[1][0];
(A) 1
(B) 2
(C) 3
(D) 4

11. What is the default value of an uninitialized global array?
(A) Garbage
(B) 0
(C) NULL
(D) Compiler dependent

12. What is the output of this code?
int arr[5];
cout << arr[0];
(A) 0
(B) Error
(C) 1
(D) Garbage value

13. Can arrays in C++ have variable size?
(A) Yes, always
(B) No, size must be constant for static arrays
(C) Only global arrays
(D) Only inside functions

14. How is memory allocated for a 2D array?
(A) Contiguous memory block row-wise
(B) Separate blocks for each row
(C) Heap only
(D) Stack only

15. How do you initialize a 2×2 array with zeros?
(A) int arr[2][2] = {0};
(B) int arr[2][2] = {{0,0},{0,0}};
(C) Both A and B
(D) None

16. What will be the output?
int arr[3] = {1,2};
cout << arr[2];
(A) 0
(B) 2
(C) Garbage
(D) Error

17. Which of the following is illegal?
(A) int arr[5] = {1,2,3,4,5};
(B) int arr[3] = {1,2,3,4};
(C) int arr[2][2] = {{1,2},{3,4}};
(D) int arr[3][3] = {{1,2},{3,4}};

18. How do you declare a 3D array?
(A) int arr(2,2,2);
(B) int arr[2,2,2];
(C) int arr[2][2][2];
(D) int arr{2,2,2};

19. What is the output of this code?
int arr[2][3] = {{1,2,3},{4,5,6}};
cout << arr[1][2];
(A) 2
(B) 3
(C) 5
(D) 6

20. How do you calculate the number of elements in a 1D array arr?
(A) sizeof(arr)/sizeof(int)
(B) sizeof(arr)/sizeof(arr[0])
(C) length(arr)
(D) arr.size()

21. Arrays in C++ are:
(A) Dynamically allocated by default
(B) Zero-based indexed
(C) One-based indexed
(D) Can hold different data types

22. What is wrong with the declaration?
int arr[];
(A) Nothing
(B) Array name is missing
(C) Size must be specified or initialized
(D) Type missing

23. Which of the following is correct for multi-dimensional array initialization?
(A) int arr[2][2] = {{1,2},{3,4}};
(B) int arr[2][2] = {1,2,3,4};
(C) Both A and B
(D) None

24. What is the output of this code?
int arr[3] = {5};
cout << arr[1];
(A) 5
(B) 0
(C) Garbage
(D) Error

25. How do you access elements in a multi-dimensional array using loops?
(A) Nested loops
(B) Single loop only
(C) Recursion only
(D) Cannot access

26. Which of the following is true about arrays in C++?
(A) Size can be changed after declaration
(B) Arrays are continuous memory blocks
(C) Can store multiple types
(D) Can store strings only

27. What will the output?
int arr[2][3] = {{1,2,3},{4,5,6}};
cout << arr[0][2];
(A) 2
(B) 3
(C) 5
(D) 6

28. Can you partially initialize a 2D array?
(A) Yes, uninitialized elements are zero
(B) No
(C) Only for 1D arrays
(D) Only for global arrays

29. Which of the following is invalid?
(A) int arr[5]; arr[5] = 10;
(B) int arr[5] = {1,2,3};
(C) int arr[2][2] = {{1,2},{3,4}};
(D) int arr[] = {1,2,3};

30. What is the output of this code?
int arr[2][2] = {{1,2},{3,4}};
cout << sizeof(arr)/sizeof(arr[0]);
(A) Error
(B) 4
(C) 8
(D) 2

31. Which of the following is true about multi-dimensional arrays?
(A) Memory is not contiguous
(B) Rows can have different lengths
(C) They are arrays of arrays
(D) Cannot store integers