Linked list class - c++

Question

The purpose of my program is to read in data from a file and build a linked list with this data and then deallocate all the nodes used.
the program also needs to print out the address of nodes after they are created and then after that they are deleted
#include <iostream>
#include <string>
#include <fstream>
#include "BigHero.h"
using namespace std;
// Linked List Struct
struct Node{
BigHero data;
Node* Next;
};
// Funtion Prototypes
int countHeros(string,int&);
void createList(BigHero,int,Node*&,Node*&,Node*&);
void printList(Node*,Node*,Node*);
void deallocateList(Node*&,Node*&,Node*&);
int main()
{
// Program Variables
Node* head;
Node* currentPtr;
Node* newNodePtr;
string Filename = "ola5party.dat"; // File string varible
int charNumber = 0; // variable to hold number of Heroes
int i = 0; // Loop control varible
countHeros(Filename,charNumber); // Function call used to count number of Heros
ifstream inFile;
inFile.open(Filename.c_str());
if(!inFile){
cout << "Error in opening file" << endl;
return 0;
}
BigHero Hero;
while(inFile)
{
inFile >> Hero;
createList(Hero,charNumber,head,currentPtr,newNodePtr);
}
printList(head,currentPtr,newNodePtr);
deallocateList(head,currentPtr,newNodePtr);
inFile.close();
return 0;
}
int countHeros(string Filename,int& charNumber)
{
ifstream inFile;
inFile.open(Filename.c_str());
string aLineStr;
while (getline(inFile, aLineStr))
{
if (!aLineStr.empty())
charNumber++;
}
inFile.close();
return charNumber;
}
void createList(BigHero Hero, int charNumber,Node*& head, Node*& currentPtr, Node*& newNodePtr)
{
head = new Node;
head->data =Hero;
currentPtr = head;
newNodePtr = new Node;
cout << "Allocated # " << newNodePtr << endl;
newNodePtr->data = Hero;
currentPtr->Next = newNodePtr;
currentPtr = newNodePtr;
}
void printList(Node* head, Node* currentPtr, Node* newNodePtr)
{
if(head != NULL)
{
currentPtr = head;
while(currentPtr->Next != NULL)
{
cout << currentPtr->data << endl;
currentPtr = currentPtr->Next;
}
}
}
void deallocateList(Node*& head ,Node*& currentPtr,Node*& newNodePtr)
{
if( head != NULL)
{
currentPtr = head;
while( head -> Next != NULL)
{
head = head->Next;
cout << "Deleting # " << head << endl;
delete currentPtr;
currentPtr = head;
}
delete head;
head = NULL;
currentPtr = NULL;
}
}
the program like this runs without errors, but here is the problem it will input all the information required but since i only have one variable hero class it is constantly replacing the information.
i tried to make a class array (example hero[i]) but cant seem to get it right and am not even sure if that is the solution. Everything is fine but i cant get the desired number of class object and i always end up with one class
this is my desired output but i only get one class object
Allocated#0x8722178
Allocated#0x87221d0
Allocated#0x8722210
Allocated#0x8722230
Allocated#0x8722288
Allocated#0x87222c8
Hero:MacWarrior­Level134,(34,16,48)­Exp:13425
Hero:LinuxMage­Level149,(24,54,21)­Exp:14926
Hero:PCBard­Level122,(18,32,17)­Exp:12221
Hero:PythonThief­Level90,(24,18,61)­Exp:9001
Hero:CplusPaladin­Level159,(31,38,29)­Exp:15925
Deleting#0x8722178
Deleting#0x87221d0
Deleting#0x8722210
Deleting#0x8722230
Deleting#0x8722288
Deleting#0x87222c8

Answer 1

It seems you have misunderstood the basic idea behind a link listed. You are not supposed to overwrite head again and again when adding element. head shall only be changed when the list is empty.
Try something like this:
struct Node
{
BigHero data;
Node* next;
};
void addNewNode(Node*& head, ....)
{
if (head == nullptr)
{
// List empty so add new node as head
head = new Node;
head->next = nullptr;
return;
}
// Find last element in list (performance can be improved with a tail*)
Node* temp = head;
while (temp->next != nullptr) temp = temp->next;
// Add new element to end of list
temp->next = new Node;
temp->next->next = nullptr
return;
}
int main()
{
Node* head = nullptr;
addNewNode(head, ....);
return 0;
}
For performance it is often good to have a tail-pointer also.
Further you should not define head in main() but make a class/struct for it and put the relevant functions in the class. Like:
struct Node
{
BigHero data;
Node* next;
};
class ListOfNode
{
public:
ListOfNode() : head(nullptr), size(0) {}
~ListOfNode()
{
// Delete all nodes
}
void addNewNode(....)
{
// ....
++size;
}
size_t size() { return size; }
private:
Node* head; // Optional: Add a tail* for better performance
size_t size;
};
int main()
{
ListOfNode list;
list.addNewNode(....);
cout << list.size() << endl;
return 0;
}