Question

in c++

Each of the member functions in WrongCode.cpp has errors in the way it performs a linked list operation. Find as many mistakes as you can

//--------------------one

void NumberList::appendNode(double num)

{

ListNode *newNode, *nodePtr;

// Allocate a new node & store num

newNode = new listNode;

newNode->value = num;

// If there are no nodes in the list

// make newNode the first node.

if (!head)

head = newNode;

else // Otherwise, insert newNode.

{

// Find the last node in the list.

while (nodePtr->next)

nodePtr = nodePtr->next;

// Insert newNode as the last node.

nodePtr->next = newNode;

}

}

//--------------------two

void NumberList::deleteNode(double num)

{

ListNode *nodePtr, *previousNode;

// If the list is empty, do nothing.

if (!head)

return;

// Determine if the first node is the one.

if (head->value == num)

delete head;

else

{

// Initialize nodePtr to head of list.

nodePtr = head;

// Skip all nodes whose value member is

// not equal to num.

while (nodePtr->value != num)

{

previousNode = nodePtr;

nodePtr = nodePtr->next;

}

// Link the previous node to the node after

// nodePtr, then delete nodePtr.

previousNode->next = nodePtr->next;

delete nodePtr;

}

//--------------------there

NumberList::~NumberList()

{

ListNode *nodePtr, *nextNode;

nodePtr = head;

while (nodePtr != nullptr)

{

nextNode = nodePtr->next;

nodePtr->next = nullptr;

nodePtr = nextNode;

}

}

Answer 1

In the above problem, I have updated the code and it is marked in bold. which are the changes in the code.

void NumberList::appendNode(double num)

{

ListNode *newNode, *nodePtr;

// Allocate a new node & store num

newNode = new listNode;

newNode->value = num;

newNode->next = NULL; // This is to be added in order to end the list.

// If there are no nodes in the list

// make newNode the first node.

if (!head)

head = newNode;

else // Otherwise, insert newNode.

{

// Find the last node in the list.
// nodePtr = head; // This is the node pointer which is to be added

while (nodePtr->next)

nodePtr = nodePtr->next;

// Insert newNode as the last node.

nodePtr->next = newNode;

}

}

//--------------------two

void NumberList::deleteNode(double num)

{

ListNode *nodePtr, *previousNode;

// If the list is empty, do nothing.

if (!head)

return;

// Determine if the first node is the one.

if (head->value == num)

nodePtr = head->next;

head = nodePtr;

delete nodePtr;

else

{

// Initialize nodePtr to head of list.

nodePtr = head;

// Skip all nodes whose value member is

// not equal to num.

while (nodePtr->value != num)

{

previousNode = nodePtr;

nodePtr = nodePtr->next;

}

// Link the previous node to the node after

// nodePtr, then delete nodePtr.

previousNode->next = nodePtr->next;

delete nodePtr;

}

//--------------------there

NumberList::~NumberList()

{

ListNode *nodePtr, *nextNode;

nodePtr = head;

while (nodePtr != nullptr)

{

nextNode = nodePtr->next;

nodePtr->next = nullptr;

delete nodePtr; // This will delete the memory allocated for the node

nodePtr = nextNode;

}

}

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