Question

Write a function double last Value (ListNode *ptr) that returns the value stored in the last node of a nonempty list passed to it as parameter. The function should print an error message and terminate the program if the list passed to it is empty.

Short answer

Question: Write a function to return the value stored in the last node of a nonempty linked list, and print an error message and terminate the program if the list passed to it is empty.

Step-by-step solution

1. Check if the list is empty

First, we will check if the list is empty by checking if the head pointer (ptr) is NULL. If it is NULL, we will print an error message and exit the program.

2. Traverse the list

Iterate through the list until the next pointer of the current node is NULL, which indicates that we have reached the last node of the list.

3. Return the last node's value

Once we have reached the last node, we will return its value (the data stored in the node). Here is the complete function in C++: ```cpp #include #include struct ListNode { double value; ListNode *next; }; double lastValue(ListNode *ptr) { // 1. Check if the list is empty if (ptr == NULL) { std::cerr << "Error: The list passed is empty." << std::endl; exit(1); } // 2. Traverse the list while (ptr->next != NULL) { ptr = ptr->next; } // 3. Return the last node's value return ptr->value; } ``` This function will return the value stored in the last node of a nonempty linked list, and will print an error message and terminate the program if the list passed to it is empty.