Chapter 18, Problem 34RQE

Program Plan Intro

Purpose of the given code:

The given code is trying to remove a value from the linked list; the value to be removed is stored in the variable “num”.

Given Code:

//Definition of function

void NumberList::deleteNode(double num)//Line 1

{//Line 2

//Declaration of structure pointer variable

ListNode *nodePtr, *previousNode; //Line 3

// If the list is empty, do nothing

if (!head)//Line 4

return;//Line 5

//Determine if the first node is the one

if (head->value == num)//Line 6

//Error #1

//Delete “head” value

delete head;//Line 7

//Error #2

else//Line 8

{//Line 9

// Initialize nodePtr to head of list

nodePtr = head;//Line 10

/* Skip all nodes whose value member is not equal to num */

while (nodePtr->value != num)//Line 11

{//Line 12

previousNode = nodePtr;//Line 13

nodePtr = nodePtr->next;//Line 14

}//Line 15

/* link the previous node to the node after nodePtr, then delete nodePtr */

previousNode->next = nodePtr->next;//Line 16

delete nodePtr;//Line 17

}//Line 18

}//Line 19