MCQs on Advanced Topics | C Programming

Dynamic Data Structures (Linked Lists, Stacks, Queues)

1. Which of the following is true about a linked list?
   • A) It allows for efficient random access
   • B) It requires contiguous memory allocation
   • C) It allows efficient insertion and deletion at both ends
   • D) It uses an array for storage
2. In a singly linked list, each node contains:
   • A) Only data
   • B) Data and a pointer to the previous node
   • C) Data and a pointer to the next node
   • D) Data and a pointer to both the previous and next node
3. What is the main advantage of a stack over a queue?
   • A) FIFO (First In, First Out) access
   • B) LIFO (Last In, First Out) access
   • C) Efficient insertion and deletion at both ends
   • D) Unlimited capacity
4. Which of the following operations is not typically associated with a stack?
   • A) Push
   • B) Pop
   • C) Peek
   • D) Dequeue
5. Which data structure is used to implement a queue?
   • A) Stack
   • B) Linked list
   • C) Array
   • D) Both B and C
6. What is the time complexity for the enqueue operation in a queue implemented using a linked list?
   • A) O(1)
   • B) O(n)
   • C) O(log n)
   • D) O(n log n)
7. What does the term “dynamic memory allocation” refer to?
   • A) Allocating memory at compile-time
   • B) Allocating memory at runtime
   • C) Allocating memory for constants
   • D) Using stack memory for data structures
8. Which of the following is an example of dynamic data structure?
   • A) Arrays
   • B) Linked Lists
   • C) Stacks
   • D) All of the above

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Memory Management in Depth

9. Which function is used to allocate memory dynamically in C?
   • A) malloc()
   • B) calloc()
   • C) realloc()
   • D) All of the above
10. What is the purpose of the free() function in C?
    • A) To allocate memory
    • B) To deallocate dynamically allocated memory
    • C) To clear memory cache
    • D) To initialize memory
11. Which of the following functions can be used to resize previously allocated memory?
    • A) malloc()
    • B) calloc()
    • C) realloc()
    • D) free()
12. What is the result of calling free() on a pointer that is already NULL?
    • A) Undefined behavior
    • B) No effect
    • C) Runtime error
    • D) Stack overflow
13. What is a memory leak in C programming?
    • A) Memory that is freed but not reused
    • B) Memory that is never allocated
    • C) Memory that is allocated but never freed
    • D) Memory that is allocated on the stack
14. How does calloc() differ from malloc()?
    • A) malloc() initializes memory to zero; calloc() does not
    • B) calloc() initializes memory to zero; malloc() does not
    • C) calloc() takes one argument; malloc() takes two
    • D) malloc() is faster than calloc()
15. What is the consequence of not freeing dynamically allocated memory?
    • A) Memory overflow
    • B) Memory leak
    • C) Stack corruption
    • D) Segmentation fault

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Function Pointers and Callbacks

16. What is a function pointer in C?
    • A) A pointer that points to a variable
    • B) A pointer that points to a function
    • C) A pointer to an array
    • D) A pointer to a struct
17. Which of the following is the correct syntax to declare a function pointer in C?
    • A) int *fptr(int a);
    • B) int (*fptr)(int a);
    • C) int fptr(*)(int a);
    • D) int (*fptr)(int*);
18. What is a callback function?
    • A) A function that calls another function
    • B) A function that gets passed as an argument to another function
    • C) A function that calls itself
    • D) A function that returns another function
19. Which of the following best describes the use of function pointers?
    • A) They allow dynamic function calls
    • B) They are used to access global variables
    • C) They are used to store constants
    • D) They allow conditional compilation
20. Which of the following is an example of passing a function as a callback?
    • A) func(callback_function);
    • B) callback_function(func);
    • C) callback(&func);
    • D) func() -> callback();
21. Which type of function is typically used as a callback function?
    • A) Functions with a fixed signature
    • B) Functions that modify global variables
    • C) Functions with no return value
    • D) Functions with variable arguments
22. What happens when a function pointer is called?
    • A) It executes the function to which it points
    • B) It allocates memory for the function
    • C) It defines a new function
    • D) It modifies the function signature

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C Standard Library Functions (stdlib.h, time.h, etc.)

23. Which function from stdlib.h is used to generate random numbers?
    • A) rand()
    • B) random()
    • C) rand_range()
    • D) randomize()
24. What does the function exit() in stdlib.h do?
    • A) Allocates memory dynamically
    • B) Terminates the program with a specified status code
    • C) Prints the program’s current state
    • D) Initiates a system shutdown
25. Which function in time.h returns the current system time?
    • A) clock()
    • B) time()
    • C) gettime()
    • D) system_time()
26. Which of the following standard library functions is used to allocate memory dynamically?
    • A) alloc()
    • B) malloc()
    • C) calloc()
    • D) realloc()
27. What does the strcmp() function from string.h do?
    • A) Copies one string to another
    • B) Compares two strings
    • C) Concatenates two strings
    • D) Checks if two strings are equal
28. Which header file is required for memory allocation functions like malloc() and free()?
    • A) stdio.h
    • B) stdlib.h
    • C) time.h
    • D) math.h
29. What does the localtime() function in time.h do?
    • A) Converts time to a readable string format
    • B) Returns the current time in GMT
    • C) Converts the time to local time representation
    • D) Sets the system time to the local time
30. Which of the following functions is used to generate random numbers within a specified range?
    • A) rand_range()
    • B) rand() % range
    • C) randomize()
    • D) generate_random()

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Advanced Pointer Concepts (Double Pointers, Array of Pointers)

31. What is a double pointer in C?
    • A) A pointer that points to another pointer
    • B) A pointer to a function
    • C) A pointer that points to a variable
    • D) A pointer that points to an array
32. Which of the following is the correct syntax for declaring a double pointer?
    • A) int **ptr;
    • B) int *ptr;
    • C) int ptr**;
    • D) int ptr[];
33. When do you typically use a double pointer in C?
    • A) When you need to dynamically allocate memory
    • B) When you need to access arrays of pointers
    • C) When passing a pointer to a function and modifying the pointer value
    • D) When working with strings
34. What does the following code do?cCopy codeint a = 10; int *ptr = &a; int **dptr = &ptr;
    • A) It creates a pointer to a pointer to an integer
    • B) It creates a pointer to an integer
    • C) It creates an array of pointers
    • D) It dereferences the pointer twice
35. How do you access the value of a variable using a double pointer?
    • A) *dptr
    • B) **dptr
    • C) dptr*
    • D) *ptr
36. What is the benefit of using an array of pointers?
    • A) It allows efficient dynamic memory allocation
    • B) It allows random access to array elements
    • C) It allows storing multiple types of data
    • D) It allows storing multiple pointers to strings
37. Which of the following is an example of an array of pointers?
    • A) int arr[5];
    • B) int *arr[5];
    • C) int *arr;
    • D) int arr[] = {1, 2, 3, 4};
38. What is the primary use case for an array of pointers?
    • A) To store multiple types of data
    • B) To store pointers to strings or arrays
    • C) To store integers and floating-point numbers
    • D) To store data in a fixed-size array
39. What will the following code output?cCopy codeint a = 5; int *p = &a; printf("%d", *p);
    • A) 5
    • B) Address of a
    • C) Undefined behavior
    • D) Error
40. Which of the following would you use to pass a pointer to a function and modify the pointer value?
    • A) Single pointer
    • B) Double pointer
    • C) Array of pointers
    • D) Function pointer

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Answers Table:

Qno	Answer
1	C) It allows efficient insertion and deletion at both ends
2	C) Data and a pointer to the next node
3	B) LIFO (Last In, First Out) access
4	D) Dequeue
5	D) Both B and C
6	A) O(1)
7	B) Allocating memory at runtime
8	B) Linked Lists
9	A) malloc()
10	B) To deallocate dynamically allocated memory
11	C) realloc()
12	B) No effect
13	C) Memory that is allocated but never freed
14	B) calloc() initializes memory to zero; malloc() does not
15	B) Memory leak
16	B) A pointer that points to a function
17	B) int (*fptr)(int a);
18	B) A function that gets passed as an argument to another function
19	A) They allow dynamic function calls
20	A) func(callback_function);
21	A) Functions with a fixed signature
22	A) It executes the function to which it points
23	A) rand()
24	B) Terminates the program with a specified status code
25	B) time()
26	B) malloc()
27	B) Compares two strings
28	B) stdlib.h
29	C) Converts the time to local time representation
30	B) rand() % range
31	A) A pointer that points to another pointer
32	A) int **ptr;
33	C) When passing a pointer to a function and modifying the pointer value
34	A) It creates a pointer to a pointer to an integer
35	B) **dptr
36	B) It allows random access to array elements
37	B) int *arr[5];
38	B) To store pointers to strings or arrays
39	A) 5
40	B) Double pointer