Question

The program I wrote has a few memory leaks. My assignment is to just fix the memory leaks. Here's the code:

#ifndef LINKEDLIST H #define LINKEDLIST.H #include <vector» #include <iostream> template<typename T> class LinkedList public: class Node public: Node) this->next-this->prev = nullptr; //this->data = 0; T data; Node *next, *prev; LinkedLis<T> head = tail = nullptr; length = 0; void AddHead(const T data) if (head == nullptr) head = new Node; head->data data; tail = head; else Node *new-node new Node; new-node->data = data; new-node->next = head; head->prev = new node; head head->prev length++;

bool RemoveTail()
{
if (tail == nullptr)
return false;
Node *ptr = tail;
if(tail->prev != nullptr)
{
tail = tail->prev;
tail->next = nullptr;
}
else
{
tail = nullptr;
head = nullptr;
}
delete ptr;
ptr = nullptr;
length--;
return true;
}

bool RemoveAt(const unsigned int index)
{
if(index >= length || index < 0)
return false;

unsigned int ctr = 0;
Node *ptr = head;
while (ptr != nullptr && ctr < index)
{
ptr = ptr->next;
ctr++;
}
if (ptr == nullptr)
{
return false;
}
else
{
if(ptr->prev != nullptr)
ptr->prev->next = ptr->next;
if(ptr->next != nullptr)
ptr->next->prev = ptr->prev;
delete ptr;
ptr = nullptr;
length--;
return true;
}
}

void AddNodesHead(const T arr[], const unsigned int count)
{
for (unsigned int i = 0; i < count; i++)
{
AddHead(arr[i]);
length++;
}
}

void AddNodesTail(const T arr[], const unsigned int count)
{
for (unsigned int i = 0; i < count; i++)
{
AddTail(arr[i]);
length++;
}
}

void InsertBefore(Node *node, const T data)
{
Node *front = head, *back = tail;
Node *ptr;
if (front == nullptr && back == nullptr)
{
AddHead(data);
return;
}
if (node == nullptr)
return;
while (front <= back)
{
if (front == node)
{
ptr = front;
break;
}
else if (back == node)
{
ptr = back;
break;
}
front = front->next;
back = back->prev;
}
Node *new_node = new Node;
new_node->data = data;
ptr->prev->next = new_node;
new_node->prev = ptr->prev;
new_node->next = ptr;
ptr->prev = new_node;
length++;
}

void InsertAfter(Node *node, const T data)
{
Node *front = head, *back = tail;
Node *ptr = nullptr;
if (front == nullptr && back == nullptr)
AddHead(data);
if (node == nullptr)
return;
while (front <= back)
{
if (front == node)
{
ptr = front;
break;
}
else if (back == node)
{
ptr = back;
break;
}
front = front->next;
back = back->prev;
}
Node *new_node = new Node;
new_node->data = data;
ptr->next->prev = new_node;
new_node->next = ptr->next;
new_node->prev = ptr;
ptr->next = new_node;
length++;
}

Node* GetNode(const unsigned int index)
{
Node *ptr = head;
for (unsigned int i = 0; i < index && ptr != nullptr; i++)
{
ptr = ptr->next;
}
return ptr;
}
Node* Find(const T val)
{
Node *front = head, *back = tail;
Node *ptr = nullptr;
if (front == nullptr && back == nullptr)
{
return nullptr;
}
while (front <= back)
{
if (front->data == val)
{
ptr = front;
break;
}
else if (back->data == val)
{
ptr = back;
break;
}
front = front->next;
back = back->prev;
}
return ptr;
}

void InsertAt(const T data, const unsigned int index)
{
Node *ptr = head;
if (index > length)
return;
else if (index == 0)
AddHead(data);
else if (index == length - 1)
AddTail(data);
else
{
for (unsigned int i = 0; i < index; i++)
{
ptr = ptr->next;
}
Node *new_node = new Node;
ptr->prev->next = new_node;
new_node->prev = ptr->prev;
new_node->next = ptr;
ptr->prev = new_node;
}
}

void FindAll(std::vector<Node*>& nodes, const T search_val)
{
Node *ptr = head;
while(ptr != nullptr)
{
if(ptr->data == search_val)
nodes.push_back(ptr);
ptr = ptr->next;
}
}

T& operator[](const unsigned int index)
{
Node *ptr = head;
for (unsigned int i = 0; i < index; i++)
{
ptr = ptr->next;
}
return ptr->data;
}

private:
unsigned int length;
Node* head, *tail;

};
#endif

Answer 1

//MODIFY AddHead AS:-

void AddHead(const T data)

{

if(head==nullptr)

{

head=new Node;

head->data=data;

tail=head;

head->prev=head->next=tail->prev=tail->next=nullptr;

}

else

{

Node *new_node=new Node;

new_node->data=data;

new_node->next=head;

head->prev=new_node;

head=new_node;

}

length++;

}

//MODIFY AddTail As:-

void AddTail(const T data)

{

if(tail==nullptr)

{

tail=new Node;

tail->data=data;

head=tail;

head->prev=head->next=tail->prev=tail->next=nullptr;

}

else

{

Node *new_node=new Node;

new_node->data=data;

new_node->prev=tail;

tail->next=new_node;

tail=new_node;

}

length++;

}

//Rest seems to be correct.If any more problem,please comment