C++ Linked List Exercises: Delete the last node of a Singly Linked List

C++ Linked List: Exercise-12 with Solution

Write a C++ program to delete the last node of a Singly Linked List.

Test Data:
Original list:
7 5 3 1
Remove the last node of the said list:
Updated list:
7 5 3
Again remove the last node of the said list:
Updated list:
7 5

Sample Solution:

C++ Code:

 #include <iostream> // Including input-output stream header file

using namespace std; // Using standard namespace

struct Node // Declare a structure for defining a Node
{   
    int num; // Data field to store a number
    Node *next; // Pointer to the next node
}; // Node constructed

int sizen = 0; // Initializing variable to keep track of the size of the linked list

// Function to insert a node at the start of the linked list
void insert(Node** head, int num){
    Node* new_Node = new Node(); // Creating a new node
    new_Node->num = num; // Assigning data to the new node
    new_Node->next = *head; // Pointing the new node to the current head
    *head = new_Node; // Making the new node as the head
    sizen++; // Increasing the size of the linked list
}

// Function to delete the last node of the linked list
Node* delete_last_node(struct Node* head) {
    if (head == NULL) // Base case: if the list is empty
        return NULL;

    if (head->next == NULL) { // Base case: if there's only one node in the list
        delete head; // Delete the head node
        return NULL;
    }

    Node* second_last_node = head; // Locate the second last node
    while (second_last_node->next->next != NULL)
        second_last_node = second_last_node->next;

    delete (second_last_node->next); // Remove the last node from the list
    second_last_node->next = NULL; // Change the next of the second last node to NULL

    return head; // Return the updated head
}

// Function to display all nodes in the linked list
void display_all_nodes(Node* node) {
    while (node != NULL) { // Loop through all nodes until the end is reached
        cout << node->num << " "; // Displaying the data in the current node
        node = node->next; // Move to the next node
    } 
}

int main() {
    Node* head = NULL; // Initializing the head of the linked list as NULL

    insert(&head,1); // Inserting a node with value 1
    insert(&head,3); // Inserting a node with value 3
    insert(&head,5); // Inserting a node with value 5
    insert(&head,7); // Inserting a node with value 7

    cout << "Original list:\n"; // Displaying message for the original list
    display_all_nodes(head); // Displaying all nodes in the original list

    cout << "\n\nRemove the last node of the said list:"; // Displaying message for removal of last node
    cout << "\nUpdated list:\n";
    head = delete_last_node(head); // Removing the last node of the list
    display_all_nodes(head); // Displaying all nodes after removal

    cout << "\n\nAgain remove the last node of the said list:"; // Displaying message for removal of last node again
    cout << "\nUpdated list:\n";
    head = delete_last_node(head); // Removing the last node of the list again
    display_all_nodes(head); // Displaying all nodes after removal

    cout << endl; // Displaying newline
    return 0; // Returning from the main function
}

Sample Output:

Original list:
7 5 3 1

Remove the last node of the said list:
Updated list:
7 5 3

Again remove the last node of the said list:
Updated list:
7 5

Flowchart:

CPP Code Editor:

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Previous C++ Exercise: Delete a middle node from a Singly Linked List.
Next C++ Exercise: Delete the n^th node of a Singly Linked List from end.