Hash Tables & Linked Lists

[StarMagic]

Hi,
I'm a java programmer and I have never used C++ before. But I have to code in C++ for an assignment. After all my research I managed to get this far and I'm totally lost. I'm supposed to implement hash tables and use linked list in the case of collisions. I would appreciate any help.

Thanks a ton.


#include <iostream>
#include <string>
#include <sstream>

using namespace std;

typedef string ObjectType;

struct ObjectNode{
ObjectType cars;
string model;
string status;
ObjectNode *next;
};

class LinkedList{
private:
ObjectNode *curNode, *headNode, *possitionNode;

public:
LinkedList(LinkedList& list);
void addRec(ObjectNode *&headNode, ObjectType cars, string status, string model);
bool isEmpty();
void printList();
};

LinkedList::LinkedList(LinkedList& list){
if(list.headNode == NULL)
headNode = NULL;
else{
headNode = new ObjectNode;
headNode->cars = list.headNode->cars;

ObjectNode *newNode = headNode;
for (ObjectNode *head = list.headNode->next; headNode != NULL; headNode = headNode->next)
{
newNode->next = new ObjectNode;
newNode = newNode->next;
newNode->cars = headNode->cars;
}
newNode->next = NULL;
}
}

void LinkedList::addRec(ObjectNode *&headNode, ObjectType cars, string status, string model){
if ((headNode == NULL) || (cars<headNode->cars))
{
ObjectNode *newNode = new ObjectNode;
newNode->cars = cars;
newNode->next = headNode;
cars<newNode->status;
cars<newNode->model;
headNode = newNode;
}
else
{
addRec(headNode->next, cars, status, model);
}
}

void LinkedList:rintList(){
ObjectNode *temp;
temp = new ObjectNode;
cout << temp->status;
cout << temp->model;
}

class HashTable{
public:
ObjectNode *indexNode;
LinkedList Table[26];
int size;
//Functions
HashTable();
void add(string newObject);
};

HashTable::HashTable(){
}

void HashTable::add(string newObject){
int index = getIndex(newObject);
indexNode = &T[index];
//indexNode.addRec(string newObject);
size++;
}

int main(){
return 0;
}

[Lindley]

Depending on precisely what the assignment says you need to do, you could use a std::list for the linked-list part.

If it weren't an assignment, I'd say just use a std::tr1::unordered_map, which is a hash table.

If you throw code tags around that, the formatting will be preserved. That makes it much easier to read.

You're doing okay for a start. The biggest problem I see right now is that you need to at the least give the LinkedList class a destructor which cleans up the dynamic memory. You should probably also give it a copy constructor and assignment operator, or else define those two private to make the class uncopyable.

[couling]

Allways use code tags correctly. You tend to get more help if you do.

In java, you can simply forget an object and java will remove the object itself. In c++ every object you create (using "new") must be deleted explicitly with "delete". Consiquently (as lindly says), you have to also write a destructor method which is responsible for calling delete on everything else that you're object created with "new".

Also,

indexNode.addRec(string newObject);
// should be
indexNode->addRec(string newObject);

If the left hand side is a pointer use "->", other wise if it is the object itself use "."

If you have any specific questions, they will be easier to answer than just "I'm lost".