C/C++ Linked Lists, Stacks, and Queues: Fundamental Concepts Quiz Quiz

Challenge your understanding of fundamental C and C++ data structures, including linked lists, stacks, and queues. This quiz highlights essential concepts, terminology, and usage to reinforce your coding foundation in these popular linear structures.

1. Linked List Basics

   In C, which component is essential for a node in a singly linked list to connect to the rest of the list?

   1. A pointer to the previous node
   2. A length variable
   3. An integer index
   4. A pointer to the next node

   Explanation: A singly linked list node in C must have a pointer to the next node to form the chain structure. Without this pointer, nodes cannot link, breaking the list. A pointer to the previous node is used in doubly linked lists, not singly ones. An integer index and a length variable are not standard for node connections.

2. Stack Operations

   What is the basic operation to remove the top element from a stack in C or C++?

   1. Pop
   2. Peek
   3. Insert
   4. Enqueue

   Explanation: The pop operation removes and returns the top element from a stack, following the Last-In-First-Out (LIFO) principle. Peek obtains the top element without removing it. Enqueue is associated with queues and insert is a general term, not specific to stacks.

3. Queue Data Structure

   When using a queue implemented with a linked list in C, where are new elements typically added?

   1. At a random position in the list
   2. At the rear (tail) of the list
   3. At the head of the list
   4. In the middle of the list

   Explanation: In queues, elements are enqueued at the rear (tail) and dequeued from the front (head), ensuring First-In-First-Out (FIFO) order. Adding at the head would violate FIFO. Inserting in the middle or at a random position does not match conventional queue behavior.

4. Null Terminator Use

   Which value is commonly used to indicate the end of a linked list in C?

   1. NULL
   2. EOF
   3. 0xFF
   4. 1

   Explanation: NULL is the standard value used to signify that there are no more nodes in a linked list by setting the next pointer to NULL. 0xFF is a hexadecimal value not typically used for this purpose. '1' is a general integer and does not represent list termination. 'EOF' signifies the end of a file, not a list.

5. Stack Underflow

   What happens if you perform a pop operation on an empty stack in C or C++?

   1. A new element is inserted
   2. The pop returns the last value again
   3. An underflow condition occurs
   4. The stack resizes automatically

   Explanation: Popping from an empty stack is called an underflow, which means no data is available to remove. Stacks do not resize automatically in most implementations. Inserting a new element is unrelated to the pop operation. Returning the last value again is incorrect; valid pops only occur when the stack is non-empty.

6. Linked List Memory

   Which function is typically used in C to allocate memory for a new node in a linked list?

   1. scanf
   2. malloc
   3. append
   4. print

   Explanation: malloc is used to dynamically allocate memory for new nodes, allowing for flexible, runtime list growth. scanf is used for input operations, not memory management. append is not a standard C function; it's a term for add operations. print is for displaying data.

7. Queue Front Operation

   In a queue, which operation removes the element that was added earliest?

   1. Dequeue
   2. Peek
   3. Push
   4. Enqueue

   Explanation: The dequeue operation removes (and often returns) the element at the front, which was added first, reflecting the FIFO order of queues. Enqueue adds new items, push relates to stacks, and peek fetches the front element without removal, not following removal behavior.

8. Circular Queue Advantage

   What is the main advantage of using a circular queue over a linear queue?

   1. Faster search times
   2. Allows random access
   3. No need for pointers
   4. Efficient use of storage

   Explanation: Circular queues make optimal use of allocated space by wrapping around when reaching the end, preventing wasted slots. Circular queues do not improve search times or eliminate the need for pointers if using linked implementations. Random access is not generally supported in queue structures.

9. Doubly Linked List

   Which type of pointer is stored in a node of a doubly linked list that is not present in a singly linked list?

   1. A pointer to the last element
   2. A pointer to the previous node
   3. A pointer to null
   4. A pointer to random elements

   Explanation: A doubly linked list node holds a pointer to both the previous and next nodes, enabling traversal in both directions. A pointer to the last element is not standard for each node. Random element pointers don’t make it a doubly linked list, and a pointer to null is not unique to this structure.

10. Stack Top Access

    How can you access the top element of a stack in C or C++ without removing it?

    1. Using the insert operation
    2. Using the pop operation
    3. Using the peek operation
    4. Using the enqueue operation

    Explanation: The peek operation provides a way to view the top element without modifying the stack. The pop operation removes the top element, not just accesses it. Enqueue is used for adding elements in queues, and insert is a generic term without such specific meaning in stack operations.