Queue implementation and array resizing using C++ - c++

The code is supposed to do queue functions which I got right.
The only problem I am having is: I am supposed to double the array size to twice its original size once the array gets completely filled.
I have coded for it but still getting garbage values when I try to put in more values than the original array size. So the problem seems to be in the inc() function below:
#ifndef Q_H_
#define Q_H_
#include <iostream>
using namespace std;
template <class elemType>
class arrayQueue
{
int size;
int *array;
int front;
int back;
int count;
public:
arrayQueue(elemType size)
{
this->size = size;
array = new int[size];
front = 0;
back = -1;
count=0;
}
bool isEmpty()
{
return (max()==0);
}
bool isFull() {
return (max()==size);
}
void enqueue(elemType entry)
{
cout << "enqueue " << entry;
if(isEmpty())
{
front = back = 0;
array[back] = entry;
count++;
}
else
{
back = (back+1) % size;
array[back] = entry;
count++;
}
cout << endl;
}
int maxsize()
{
return count;
}
void dequeue() {
cout << "dequeue : " << Front();
if(isEmpty())
{
cout << " error : empty";
}
else if(back == front)
{
back = front = -1;
}
else
{
front = (front+1) % size;
count--;
}
cout << endl;
}
void print()
{
if(isEmpty())
{
cout << "Queue is empty";
}
else
{
for(int i = front; i<count; i++)
{
cout << array[i] << " ";
}
cout << array[back];
}
//cout<<"count is:" <<count<<endl;
cout << endl;
}
int Front()
{
if(front == -1)
{
cout<<"Queue is empty\n";
return -1;
}
return array[front];
}
int Back()
{
if(back==-1)
{
cout<<"Queue is full";
}
return array[back];
}
int max()
{
return count;
cout <<"count: " <<count;
}
void inc()
{
int newsize = this->size*2;
elemType *temp = new elemType[newsize];
for (int i=0; i<this->count;i++)
{
temp[i]=this->array[(front+i) % size];
}
delete [] this->array;
this->array=temp;
this->count=newsize;
// front=array[front]; //0
//front = 0;
//back=count;
}
};
#endif /* Q_H_ */
I would really appreciate help with this.

three small changes:
enqueue method: inc when isFull
if (isFull())
{
inc();
}
print method: print every element from front to back
inc method: copy every element from front to back, and reset front and back index
void inc()
{
int newsize = this->size*2;
elemType *temp = new elemType[newsize];
// ******* IMPORTANT ******
// copy count elements
for (int i = 0; i < count; ++i) {
int index = (front + i) % size;
temp[i] = array[index];
}
front = 0;
back = count - 1;
delete []array;
array=temp;
count=newsize;
}
template <class elemType>
class arrayQueue
{
int size;
int *array;
int front;
int back;
int count;
public:
arrayQueue(elemType size)
{
this->size = size;
array = new int[size];
front = 0;
back = -1;
count=0;
}
bool isEmpty()
{
return (max()==0);
}
bool isFull() {
return (max()==size);
}
void enqueue(elemType entry)
{
cout << "enqueue " << entry;
if(isEmpty())
{
front = back = 0;
array[back] = entry;
count++;
}
else
{
if (isFull()) {
inc();
}
back = (back+1) % size;
array[back] = entry;
count++;
}
cout << endl;
}
int maxsize()
{
return count;
}
void dequeue() {
cout << "dequeue : " << Front();
if(isEmpty())
{
cout << " error : empty";
}
else if(back == front)
{
back = front = -1;
}
else
{
front = (front+1) % size;
count--;
}
cout << endl;
}
void print()
{
if(isEmpty())
{
cout << "Queue is empty";
}
else
{
// ******* IMPORTANT ******
for (int i = 0; i < count; ++i) {
int index = (front + i) % size;
cout << array[index] << " ";
}
}
//cout<<"count is:" <<count<<endl;
cout << endl;
}
int Front()
{
if(front == -1)
{
cout<<"Queue is empty\n";
return -1;
}
return array[front];
}
int Back()
{
if(back==-1)
{
cout<<"Queue is full";
}
return array[back];
}
int max()
{
return count;
cout <<"count: " <<count;
}
void inc()
{
int newsize = this->size*2;
elemType *temp = new elemType[newsize];
// ******* IMPORTANT ******
// copy count elements
for (int i = 0; i < count; ++i) {
int index = (front + i) % size;
temp[i] = array[index];
}
front = 0;
back = count - 1;
delete []array;
array = temp;
count = newsize;
}
};

Since you move elements to the beginning of the newly allocated array, inc needs to update front and back to refer to their respective new positions.
Also, you're updating count to be the new size instead of size.

Related

Having trouble printing a chained Hashtable c++

#include <iostream>
#include <list>
using namespace std;
const int TABLESIZE = 3;
class HashTable
{
public:
string k;
int v;
HashTable* next;
HashTable(string k, int v)
{
this->k = k;
this->v = v;
next = NULL;
}
};
class HashMapTable
{
private:
HashTable **t;
public:
HashMapTable()
{
t = new HashTable * [TABLESIZE];
for (int i = 0; i < TABLESIZE; i++)
{
t[i] = NULL;
}
}
int HashFunction(int v)
{
return v % TABLESIZE;
}
void Insert(string k, int v)
{
int hV = HashFunction(v);
HashTable* p = NULL;
HashTable* en = t[hV];
while (en!= NULL)
{
p = en;
en = en->next;
}
if (en == NULL)
{
en = new HashTable(k, v);
if (p == NULL)
{
t[hV] = en;
} else
{
p->next = en;
}
} else
{
en->v = v;
}
}
void PrintTable()
{
for (int i = 0; i < TABLESIZE; i++)
{
if(t[i] != NULL)
{
cout << t[i]->k << " " << t[i]->v << endl;
}
}
}
~HashMapTable()
{
for (int i = 0; i < TABLESIZE; i++)
{
if (t[i] != NULL)
delete t[i];
delete[] t;
}
}
};
int main()
{
HashMapTable HT;
cout << "entering the pairs now" << endl;
HT.Insert("Boramir", 25);
HT.Insert("Legolas", 101);
HT.Insert("Gandalf", 49);
cout << "printing the pairs now" << endl;
HT.PrintTable();
}
My issue is that not all the key value pairs in the table are being printed depending on the table size. If it's 3 (the desired amount) only 2 print, but if it's at least 7, they all print? I'm not sure what piece of my code is causing this to happen. Also, if there are multiple pairs in one bucket, the second/third/etc pair doesn't print and I'm not sure why. Thanks for any help.

My C++ program returns EXC_BAD_ACCESS in Xcode ONLY

I made a program that involves a binary search tree. Basically, my segregates a set of input integers into "bins" in such a way that each bin are equal in value when their contents are summed.
#include <iostream>
#include <vector>
#ifndef DEBUG
#define DEBUG 0
#endif
using namespace std;
class Node {
private:
int weight = 0;
Node* leftNode;
Node* rightNode;
int bin = 0;
public:
Node() {}
Node(int weight) {
this->weight = weight;
}
void printContents() {
cout << weight << " ";
if(leftNode) leftNode->printContents();
if(rightNode) rightNode->printContents();
}
void addNode(Node* node) {
if(node->getWeight() <= this->weight) {
if(leftNode) leftNode->addNode(node);
else leftNode = node;
} else {
if(rightNode) rightNode->addNode(node);
else rightNode = node;
}
}
Node* getNode(int weight) {
if(!hasChildren()) {
if(this->weight == weight && bin == 0) return this;
else return nullptr;
} else {
Node* n = nullptr;
if(this->weight == weight && bin == 0) {
n = this;
}
Node* child;
if(leftNode && weight <= this->weight) {
child = leftNode->getNode(weight);
} else if(rightNode && weight > this->weight) {
child = rightNode->getNode(weight);
} else {
child = nullptr;
}
if(child) {
return child;
}
else return n;
}
}
bool hasChildren() {
if(leftNode || rightNode) return true;
else return false;
}
int getWeight() {
return weight;
}
void setBin(int bin) {
this->bin = bin;
}
int getBin() {
return bin;
}
void unbin() {
bin = 0;
}
void operator=(Node* node) {
this->weight = node->weight;
this->leftNode = node->leftNode;
this->rightNode = node->rightNode;
this->bin = node->bin;
}
};
class Bin {
private:
int binNum = 0;
int weight = 0;
int targetWeight = 0;
vector<Node*> nodes;
public:
Bin(int binNum, int targetWeight) {
this->binNum = binNum;
this->targetWeight = targetWeight;
}
void addNode(Node* node) {
weight += node->getWeight();
node->setBin(binNum);
nodes.push_back(node);
}
Node* removeLatestNode() {
Node* n = nodes.back();
weight -= n->getWeight();
nodes.pop_back();
n->unbin();
return n;
}
int getWeight() {
return weight;
}
bool isFull() {
if(weight == targetWeight) return true;
else return false;
}
bool willBeOverloaded(int x) {
if(weight + x > targetWeight) return true;
else return false;
}
};
void organize(Node* rootNode, int bins, int weightPerBin) {
#if DEBUG
cout << "Weight per bin: " << weightPerBin << endl;
#endif
for(int i = 1; i <= bins; i++) {
Bin bin(i, weightPerBin);
int x = weightPerBin;
while(!bin.isFull()) {
while(x > 0) {
Node* n = rootNode->getNode(x);
if (n) {
#if DEBUG
cout << "bin " << i << " : ";
cout << n->getWeight() << endl;
#endif
if (!bin.willBeOverloaded(n->getWeight())) {
#if DEBUG
cout << "adding to bin " << i << " : " << n->getWeight() << endl;
#endif
bin.addNode(n);
x = weightPerBin - bin.getWeight();
if(bin.isFull()) break;
} else {
x--;
}
} else {
x--;
}
}
if(!bin.isFull()) {
Node* n = bin.removeLatestNode();
#if DEBUG
cout << "removing from bin " << i << " : " << n->getWeight() << endl;
#endif
x = n->getWeight() - 1;
}
}
}
}
int getWeightPerBin(int* weights, int n, int bins) {
int weight = 0;
for(int i = 0; i < n; i++) {
weight += weights[i];
}
return weight/bins;
}
int main() {
int n;
int *weights;
int bins;
cin >> n;
weights = new int[n];
for(int i = 0; i < n; i++)
cin >> weights[i];
cin >> bins;
Node nodes[n];
nodes[0] = new Node(weights[0]); //the root node
for(int i = 1; i < n; i++) {
nodes[i] = new Node(weights[i]);
nodes[0].addNode(&nodes[i]);
}
organize(&nodes[0], bins, getWeightPerBin(weights, n, bins));
for(int i = 0; i < n; i++) {
cout << nodes[i].getBin() << " ";
}
return 0;
}
I developed this program in CLion IDE and it works perfectly. Recently I discovered that Xcode can also be used to develop C++ programs so I tried using it with the exact same code. But when I run the program, it always returns:
xcode error screenshot
It returns an error called EXC_BAD_ACCESS which is the first time I've encountered it. I'm a student who has a good background in Java and is currently learning C++ for a class. My knowledge in C++ is limited and I'd like to know whether this problem is due to Xcode or is inherent in my code.
You don't initialize leftNode and rightNode - they are not magically initialized to nullptr, so calling a function like
void printContents() {
cout << weight << " ";
if(leftNode) leftNode->printContents();
if(rightNode) rightNode->printContents();
}
will have Undefined Behaviour.
I suggest you initialize your variables before using them.

How to Visit Each Node in Chained Hash Table Linked Lists

I am writing chained hash table code.
I do not understand why my linked list traversal does not stop at NULL when I set entry->next->next = NULL after I insert.
I have omitted code which is not useful for my question:
What is causing the linked list traversal in `printTable' to loop forever?
ChainHash.h:
class Entry {
private:
string key;
int value;
Entry *next;
friend class HashTable_CH;
public:
Entry(string k, int v) {
key = k;
value = v;
next = NULL;
}
};
class HashTable_CH {
private:
Entry **slots;
const int DEFAULT_CAP = 11;
const float load_factor = 0.5;
int capacity;
int size;
//int isPrime(int n) {
//int calculateGrowSize() {
int hash(string k) {
int c = 0;
for (int i = 0; i < k.length(); i++)
c += int(k[i]);
return c % capacity;
}
//int probe(int hash, int index) {
public:
HashTable_CH() {
slots = new Entry*[DEFAULT_CAP];
capacity = DEFAULT_CAP;
size = 0;
for (int i = 0; i < DEFAULT_CAP; i++)
slots[i] = NULL;
}
void Insert(string key, int value) {
if (float(size) / float(capacity) >= load_factor)
//grow();
return;
int h = hash(key);
if (slots[h] == NULL) {
slots[h] = new Entry(key, value);
size++;
return;
} else {
Entry *entry = slots[h];
while (entry->next != NULL)
entry = entry->next;
entry->next = new Entry(key, value);
entry->next->next = NULL;
}
}
//bool Search(string, int &value) {
//void Remove(string key) {
void printTable() {
for (int i = 0; i < capacity; i++) {
cout << "Slot " << i << ": ";
if (slots[i] == NULL)
cout << "*****";
else {
Entry **temp = slots;
while (temp != NULL) {
cout << "Key: " << slots[i]->key << ", " << slots[i]->value;
}
}
} cout << "\n";
} cout << "\n";
}
};
testChainedHash.cpp:
#include"ChainHash.h"
int main() {
HashTable_CH t1;
t1.Insert("froyo", 500);
t1.Insert("froyo", 600);
t1.Insert("froyo", 700);
t1.printTable();
}
Here:
while (temp != NULL) {
cout << "Key: " << slots[i]->key << ", " << slots[i]->value;
}
Do you see the problem?

Reversing a singly-linked list in C++

I am having an issue with my attempt at recursively reversing my implementation of a singly-linked list.
I have read other similar questions regarding this process, however, in my attempt at implementing this process in my own program, I've come up short.
This is my attempt below (which is slightly different than what is presented in the code that follows thereafter):
Note: My list uses a root pointer which holds no significant data, and serves only as an address with which to reference data in the list.
void IntList::reverse(Node* t_node) {
if(t_node == NULL) {
reverse(root);
} else
if(t_node->next == NULL) {
cout << "In (swapping): " << t_node->value << endl;
root->next = t_node;
} else {
cout << "In: " << t_node->value << endl;
Node* tmp = t_node->next;
reverse(t_node->next);
tmp->next = t_node;
}
return NULL;
}
I lose reference somewhere and print endlessly when trying to display the list. I am really at a loss as to what the error I've made is, but suspect it may have something to do with how I handle my root.
Here is the program in its entirety (all functioning apart from the reverse() methods) for completeness.
#ifndef INTLIST_H
#define INTLIST_H
#include<iostream>
using namespace std;
class IntList {
private:
struct Node {
int value;
Node* next;
};
int size;
Node* root;
void destroy();
public:
IntList() { root = new Node; root->next = 0; root-> value = 0; size = 0;}
IntList(const IntList& list) { this->root = list.root; this->size = list.size; }
~IntList() {}
void appendNode(int val);
void insertNode(int pos, int val);
void deleteNode(int pos);
int searchNode(int val);
int getSize() const;
void print() const;
Node* reverse(Node* t_node);
int &operator[](int element) const;
void pop_back();
void pop_front();
void push_back(int val);
void push_front(int val);
};
void IntList::appendNode(int val) {
push_back(val);
}
void IntList::insertNode(int pos, int val) {
Node* tmp;
Node* current = root;
for(int i = 0; i < pos && current->next != NULL; i++) {
current = current->next;
}
tmp = new Node;
tmp->value = val;
tmp->next = current->next;
current->next = tmp;
size++;
}
void IntList::deleteNode(int pos) {
Node* tmp;
Node* current = root;
if(pos <= size-1) {
for(int i = 0; i < pos; i++) {
current = current->next;
}
tmp = current->next;
current->next = tmp->next;
delete tmp;
size--;
} else {
cout << "ERROR: Out of range." << endl;
}
}
int IntList::searchNode(int val) {
int position = 0;
Node* current = root->next;
if(size != 0) {
for(position = 0; position < size && current->value != val; position++) {
current = current->next;
}
} else {
cout << "ERROR: List is empty." << endl;
position = -1;
}
return position;
}
int IntList::getSize() const {
return size;
}
void IntList::print() const {
Node* current = root->next;
cout << "List: ";
while(current != NULL) {
cout << current->value << " ";
current = current->next;
}
if(getSize() == 0) {
cout << "Empty.";
}
cout << endl;
}
IntList::Node* IntList::reverse(Node* t_node) {
#define REVERSE
#ifndef REVERSE
if(t_node == NULL) {
reverse(root);
} else
if(t_node->next == NULL) {
cout << "In (swapping): " << t_node->value << endl;
root->next = t_node;
} else {
cout << "In: " << t_node->value << endl;
Node* tmp = t_node->next;
reverse(t_node->next);
tmp->next = t_node;
}
#endif //reverses list, but causes infinite loop in display
return NULL;
}
int &IntList::operator[](int pos) const {
Node* current = root->next;
if(pos <= size-1) {
for(int i = 0; i < pos; i++) {
current = current->next;
}
} else {
cout << "ERROR: Out of bounds.";
current = NULL;
}
return current->value;
}
void IntList::pop_back() {
deleteNode(size-1);
}
void IntList::pop_front() {
deleteNode(0);
}
void IntList::push_back(int val) {
insertNode(size, val);
}
void IntList::push_front(int val) {
insertNode(0, val);
}
#endif
#ifndef LINKEDLIST_H
#define LINKEDLIST_H
#include<iostream>
using namespace std;
template<typename T>
class LinkedList {
private:
struct Node {
T value;
Node* next;
};
int size;
Node* root;
void destroy();
public:
LinkedList() { root = new Node; root->next = 0; root-> value = 0; size = 0;}
LinkedList(const LinkedList &) {}
~LinkedList() {}
void appendNode(T val);
void insertNode(int pos, T val);
void deleteNode(int pos);
int searchNode(T val);
int getSize() const;
void print() const;
void reverse(Node* t_node);
int &operator[](int element) const;
void pop_back();
void pop_front();
void push_back(T val);
void push_front(T val);
};
template <typename T>
void LinkedList<T>::appendNode(T val) {
push_back(val);
}
template <typename T>
void LinkedList<T>::insertNode(int pos, T val) {
Node* tmp;
Node* current = root;
for(int i = 0; i < pos && current->next != NULL; i++) {
current = current->next;
}
tmp = new Node;
tmp->value = val;
tmp->next = current->next;
current->next = tmp;
size++;
}
template <typename T>
void LinkedList<T>::deleteNode(int pos) {
Node* tmp;
Node* current = root;
if(pos <= size-1) {
for(int i = 0; i < pos; i++) {
current = current->next;
}
tmp = current->next;
current->next = tmp->next;
delete tmp;
size--;
} else {
cout << "ERROR: Out of range." << endl;
}
}
template <typename T>
int LinkedList<T>::searchNode(T val) {
int position = 0;
Node* current = root->next;
if(size != 0) {
for(position = 0; position < size && current->value != val; position++) {
current = current->next;
}
} else {
cout << "ERROR: List is empty." << endl;
position = -1;
}
return position;
}
template <typename T>
int LinkedList<T>::getSize() const {
return size;
}
template <typename T>
void LinkedList<T>::print() const {
Node* current = root->next;
cout << "List: ";
while(current != NULL) {
cout << current->value << " ";
current = current->next;
}
if(getSize() == 0) {
cout << "Empty.";
}
cout << endl;
}
template <typename T>
void LinkedList<T>::reverse(Node* t_node) {
/*
if(t_node == NULL) {
reverse(root);
} else
if(t_node->next == NULL) {
cout << "In (swapping): " << t_node->value << endl;
root->next = t_node;
} else {
cout << "In: " << t_node->value << endl;
Node* tmp = t_node->next;
reverse(t_node->next);
tmp->next = t_node;
}
*/ //reverses list, but causes infinite loop in display
}
template <typename T>
int &LinkedList<T>::operator[](int pos) const {
Node* current = root->next;
if(pos <= size-1) {
for(int i = 0; i < pos; i++) {
current = current->next;
}
} else {
cout << "ERROR: Out of bounds.";
current = NULL;
}
return current->value;
}
template <typename T>
void LinkedList<T>::pop_back() {
deleteNode(size-1);
}
template <typename T>
void LinkedList<T>::pop_front() {
deleteNode(0);
}
template <typename T>
void LinkedList<T>::push_back(T val) {
insertNode(size, val);
}
template <typename T>
void LinkedList<T>::push_front(T val) {
insertNode(0, val);
}
#endif
//test driver
int main() {
IntList i_list;
int n;
cout << "Appending node: value = " << 0 << endl;
i_list.appendNode(0);
i_list.print();
cout << endl;
n = 5;
cout << "Inserting nodes (at their values). Node values = { ";
for(int i = 0; i < n; i++) {
cout << i << " ";
i_list.insertNode(i,i);
}
cout << "}" << endl;
i_list.print();
cout << endl;
cout << "Deleting node at position: " << i_list.getSize()-1 << endl;
i_list.deleteNode(i_list.getSize()-1);
i_list.print();
cout << endl;
cout << "Searching for value: " << 3 << endl;
cout << "Found at: " << i_list.searchNode(3) << endl;
cout << endl;
i_list.print();
cout << "List size: " << i_list.getSize() << endl;
cout << endl;
n = 3;
cout << "Calling node at list[" << n << "]: " << i_list[n] << endl;
cout << endl;
i_list.print();
cout << "Deleting node from back position." << endl;
i_list.pop_back();
i_list.print();
cout << endl;
i_list.print();
cout << "Deleting node from front position." << endl;
i_list.pop_front();
i_list.print();
cout << endl;
n = 9;
i_list.print();
cout << "Adding node (value = " << n << ") to back position." << endl;
i_list.push_back(n);
i_list.print();
cout << endl;
n = 8;
i_list.print();
cout << "Adding node (value = " << n << ") to front position." << endl;
i_list.push_front(n);
i_list.print();
cout << endl;
i_list.print();
cout << "Copying list to new list." << endl;
IntList t_list(i_list);
cout << endl;
cout << "List copy:" << endl;
t_list.print();
cout << endl;
/*
* Showing functionality transfers over to LinkedList template class
* generally, for primitive data types (lacks absolutely generality
* for data which can't be passed directly to cout).
*/
cout << "List functionality transfers generally to LinkedList class:" << endl;
LinkedList<int> int_list;
LinkedList<double> double_list;
LinkedList<char> char_list;
cout << "Appending nodes:" << endl;
n = 5;
for(int i = 0; i < n; i++){
int_list.appendNode(i);
}
int_list.print();
n = 5;
for(int i = 0; i < n; i++){
double_list.appendNode(i+0.1);
}
double_list.print();
n = 5;
for(int i = 0; i < n; i++){
char_list.appendNode('A' + i);
}
char_list.print();
cout << "Removing nodes:" << endl;
n = 5;
for(int i = 0; i < n; i++){
int_list.pop_back();
}
int_list.print();
n = 5;
for(int i = 0; i < n; i++){
double_list.pop_back();
}
double_list.print();
n = 5;
for(int i = 0; i < n; i++){
char_list.pop_back();
}
char_list.print();
return 0;
}
EDIT: I've revised my algorithm, and I believe it works algorithmically, but functionally it may be doing something which is causing a memory issue. I'm not sure as to why that may be, but here it is:
void IntList::reverse() {
IntList tmp(*this);
int list_size = size;
for(int i = 0; i < list_size; i++) {
this->insertNode(i, tmp[tmp.getSize()-1]);
this->pop_back();
tmp.pop_back();
}
}
In fact, if my [] operator overload were functioning within this method (which for some reason it is not?) I could do away with the tmp list and just reference the last value in the list directly as this[size-1].
What is the issue here?
Your problem is that after the reverse() the last element in your list will point to the root element instead of pointing to null. One solution could be an explicit check for that condition so you would get:
void IntList::reverse(Node* t_node) {
if(t_node == NULL) {
reverse(root);
return;
}
if(t_node->next == NULL) {
cout << "In (swapping): " << t_node->value << endl;
root->next = t_node;
} else {
cout << "In: " << t_node->value << endl;
Node* tmp = t_node->next;
reverse(t_node->next);
// If this node was the first node it will now be the last
if (t_node == root) {
tmp->next = NULL;
} else {
tmp->next = t_node;
}
}
}
That doesn't work if it should be possible to reverse a subpart of the list though. If that is something you need, then you probably need to use a helper function which handles all elements but the first one.
Suppose we have the IntList {1,2,3}, which actually has this form:
0 -> 1 -> 2 -> 3
Then we call reverse(root), so that t_node has the same value as root (and therefore points to (0)).
Node* tmp = t_node->next;
So tmp points to (1).
reverse(t_node->next);
Suppose this works, and the list is now 0->1->3->2
tmp->next = t_node;
So now 1->0. The list is now a loop, and the other nodes have been lost.
It is not clear what you intended this function to do, but you must have misunderstood something.
EDIT: You are attempting a high-level solution when you do not understand the low-level mechanics.
Your copy constructor:
IntList(const IntList& list) { this->root = list.root; this->size = list.size; }
performs what we call a "shallow copy"; it copies the pointer members, but not the things they point to. If you have a list A that looks like this:
0->1->2->3
and then call IntList B(A);, you'll get something that looks like this:
0
|
v
0->1->2->3
If you then call A.pop_back() and B.pop_back(), what do you think will happen?
And more to the point, what are you trying to do? Do you want to know how to write a recursive function, or is that no longer necessary?

user defined hash table with value as function pointer

Below is my code
to create hashtable with key as Char* and value as Function pointer
// hash1.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <iostream>
#include <cstdlib>
#include <cstring>
#include <iomanip>
#define SIZE_KEY 16
#define SIZE_VALUE1 64
#define SIZE_VALUE2 16
#define DEFAULT_TABLESIZE 101
using namespace std;
typedef void (*FunctionPtr)();
typedef void (*FunctionPtr1)();
void (*FunctionPtr2)();
void ping(){
cout<<"hello";
}
void refresh(){
cout<<"refresh";
}
typedef struct NODE
{
NODE(char* Key1,FunctionPtr func_ptr)
{
strcpy_s(Key,Key1);
FunctionPtr1 func_ptr1;
func_ptr1=func_ptr;
next = NULL;
}
NODE(){
}
char Key[SIZE_KEY];
FunctionPtr1 func_ptr1[SIZE_VALUE1];
NODE *next;
};
class Hashtable
{
private:
int table_size;
NODE** table;
int size;
long hashString(char* Key);
NODE* find(char* Key);
NODE* current_entry;
public:
int current_index;
Hashtable(int T = DEFAULT_TABLESIZE);//constructor
virtual ~Hashtable();//destructor
bool put(NODE *);
bool get(NODE *);
bool contains(char* Key);
void removeAll();
int getSize();
void initIterator();
bool hasNext();
void getNextKey(char* Key);
friend void disp(NODE *);
};
Hashtable::Hashtable(int T)
{
size = 0;
table_size = T;
table = new NODE*[table_size];
for(int i=0; i<table_size; i++)
{
table[i] = NULL;
}
}
Hashtable::~Hashtable()
{
removeAll();
delete[] table;
}
bool Hashtable::put(NODE *N)
{//start put
if(find(N->Key) != NULL)
{
return false;
}
//NODE* entry = new NODE( N->Key ,*(FunctionPtr *)N->func_ptr1 );
NODE* entry = new NODE( N->Key ,*(FunctionPtr *)N->func_ptr1 );
int bucket = hashString(N->Key);
entry->next = table[bucket];
table[bucket] = entry;
size++;
return true;
}//end put
bool Hashtable::get(NODE* N)
{//start get
NODE* temp = find(N->Key);
if(temp == NULL)
{
*(FunctionPtr *)N->func_ptr1 = refresh;
return false;
}
else
{
*(FunctionPtr *)N->func_ptr1= *(FunctionPtr *)temp->func_ptr1;
return true;
}
}//end get
bool Hashtable::contains(char* Key)
{//start contains
if(find(Key) == NULL)
{
return false;
}
else
{
return true;
}
}//end contains
void Hashtable::removeAll()
{//start removeAll
for(int i=0; i<table_size; i++)
{
NODE* temp = table[i];
while(temp != NULL)
{
NODE* next = temp->next;
disp(temp);
delete temp;
temp = next;
}
}
size = 0;
}//end removeAll
int Hashtable::getSize()
{
return size;
}
NODE* Hashtable::find(char* Key)
{ //start find
int bucket = hashString(Key);
NODE* temp = table[bucket];
while(temp != NULL)
{
if(strcmp(Key, temp->Key) == 0)
{
return temp;
}
temp = temp->next;
}
return NULL;
}//end find
long Hashtable::hashString(char* Key)
{//start hashString
int n = strlen(Key);
long h = 0;
for(int i=0; i<n; i++)
{
//To get almost fair distributions of NODEs over the array
h = (h << 3) ^ Key[i];
}
return abs(h % table_size );
}//end hashString
void Hashtable::initIterator()
{//start initIterator
current_entry = NULL;
current_index = table_size;
for(int i=0; i<table_size; i++)
{
if(table[i] == NULL)
{
continue;
}
else
{
current_entry = table[i];
current_index = i;
break;
}
}
}//end initIterator
bool Hashtable::hasNext()
{
if(current_entry == NULL)
{
return false;
}
else
{
return true;
}
}
void Hashtable::getNextKey(char* Key)
{
if(current_entry == NULL)
{
Key[0] = '\0';
return;
}
strcpy(Key, current_entry->Key);
if(current_entry->next != NULL)
{
current_entry = current_entry->next;
}
else
{
for(int i=current_index+1; i<table_size; i++)
{
if(table[i] == NULL)
{
continue;
}
current_entry = table[i];
current_index = i;
return;
}
current_entry = NULL;
current_index = table_size;
}
}
void dispAll(Hashtable* hashtable);
int main()
{
char temp1[SIZE_KEY];
Hashtable* hashtable = new Hashtable();
NODE N1("1",ping);
if(!hashtable->contains(N1.Key))
{
cout << "\nAdding NODE: ";
disp(&N1);
hashtable->put(&N1);
}
// dispAll(hashtable);
strcpy(N1.Key, "314");
*(FunctionPtr *) N1.func_ptr1=refresh;
if(!hashtable->contains(N1.Key))
{
cout << "\nAdding NODE: ";
disp(&N1);
hashtable->put(&N1);
}
/* strcpy(N1.Key, "320");
*(FunctionPtr *) N1.func_ptr1= ping;
if(!hashtable->contains(N1.Key))
{
cout << "\nAdding NODE: ";
disp(&N1);
hashtable->put(&N1);
}
strcpy(N1.Key, "768");
*(FunctionPtr *)N1.func_ptr1= refresh;
if(!hashtable->contains(N1.Key))
{
cout << "\nAdding node: ";
disp(&N1);
hashtable->put(&N1);
}
strcpy(N1.Key, "756");
*(FunctionPtr *) N1.func_ptr1= refresh;
if(!hashtable->contains(N1.Key))
{
cout << "\nAdding node: ";
disp(&N1);
hashtable->put(&N1);
} */
dispAll(hashtable);
// strcpy(temp1,"314");
// hashtable->remove(temp1);
// cout << "\n\nAfter removing 314:" << endl;
// dispAll(hashtable);
cout << "\n\nDestroying hashtable:" << endl;
delete hashtable;
return 0;
}
void disp(NODE *N1)
{
cout << "\nKey: " << N1->Key << "\nFunction "
<< N1->func_ptr1 << endl;
// FunctionPtr2();
}
void dispAll(Hashtable *hashtable)
{
NODE N1;
cout << "\n\nCurrent nodes in hashtable:" << endl;
hashtable->initIterator();
while(hashtable->hasNext())
{
//cout<<"Current Index === "<<hashtable->current_index;
hashtable->getNextKey(N1.Key);
hashtable->get(&N1);
disp(&N1);
}
}
each time data is written in hash table VALUE cointains the same address :(
i want address of particular function that i will send..
Some of the problems may be in struct NODE.
typedef struct NODE
{
NODE(char* Key1,FunctionPtr func_ptr)
{
strcpy_s(Key,Key1);
FunctionPtr1 func_ptr1; // <-- Problem may be here
func_ptr1=func_ptr;
next = NULL;
}
NODE(){
}
char Key[SIZE_KEY];
FunctionPtr1 func_ptr1[SIZE_VALUE1]; // <-- And here
NODE *next;
};
You declared a local func_ptr1 in NODE::NODE(char*, FunctionPtr), and assign the parameter func_ptr to func_ptr1. Thus, func_ptr is assigned to a local variable, not a member variable. And, once the constructor returns, nothing about the function pointer is remembered.
Another problem: why is NODE::func_ptr1 an array of FunctionPtr1? I don't think you intended to store multiple function pointers in one NODE instance.