Segmentation Error: Help on the correct allocation memory when saving & loading binary files containing a specific structure from a class - class

This is my first time asking a question, so apologies if it is not done 100%:
I have a class which saves and loads a binary file with a specific data structure.
If the program creates an instance of the class, save the binary file, and creates another instance of the class to load/read the binary file consequently, everything seems 100% correct.
However, if I run the program to save the binary file and then run it again to load/read that binary file, it gives me a segmentation fault at the end.
The program still does everything it needs to do before the segmentation fault, except deconstructing the class at the end (obviously).
It looks like my allocation of the memory is not correct, but I am not sure where I am going wrong.
A simplified version of the code follow (also here: https://github.com/LenteDreyer/Tests.git )
Can someone see where I am going wrong?
class header file that save/loads the file
#ifndef __TESTS_MAP_HH__
#define __TESTS_MAP_HH__
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <algorithm>
#include <sstream>
typedef struct test_struct{
bool test_bool;
double test_double;
std::vector<double> test_vector;
} test_struct_t;
class map
{
private:
std::string m_path, m_str;
double m_double;
test_struct m_struct;
public:
map(const std::string& a_id);
void set_str(std::string a_str);
void set_double(double a_double);
void set_struct(test_struct a_struct);
void load_file();
void save_file() const;
void show_file() const;
~map();
};
#endif //__TESTS_MAP_HH__
class source file that save/loads the binary file
#include "map.hh"
map::map(const std::string& a_id)
{
m_path = a_id + ".bin";
m_str = "none";
m_double = 0.0;
m_struct = {false, 0.0};
}
void map::set_str(std::string a_str){
m_str = a_str;
}
void map::set_double(double a_double){
m_double = a_double;
}
void map::set_struct(test_struct a_struct){
m_struct = a_struct;
}
void map::load_file(){
std::ifstream l_inF;
l_inF.open(m_path.c_str(), std::ios::binary | std::ios::in);
l_inF.read((char*)&m_double,sizeof(double));
l_inF.read((char*)&m_struct,sizeof(test_struct_t));
size_t str_size;
l_inF.read((char*)&str_size, sizeof(str_size));
m_str.resize(str_size);
l_inF.read((char*)&m_str[0], str_size);
l_inF.close();
}
void map::save_file() const{
std::ofstream l_outF;
l_outF.open(m_path.c_str(), std::ios::binary | std::ios::out);
l_outF.write((char*)&m_double,sizeof(double));
l_outF.write((char*)&m_struct,sizeof(test_struct_t));
size_t str_size = m_str.size();
l_outF.write((char*)&str_size, sizeof(str_size));
l_outF.write((char*)&m_str[0], str_size);
l_outF.close();
}
void map::show_file() const{
std::cout << ">>-----------------------------------------------" << std::endl;
std::cout << ">> double : " << m_double << std::endl;
std::cout << ">> double : " << m_double << std::endl;
std::cout << ">> struct.bool : " << m_struct.test_bool << std::endl;
std::cout << ">> struct.double : " << m_struct.test_double << std::endl;
std::cout << ">> struct.vector : " << "size = " << m_struct.test_vector.size() << std::endl;
std::cout << ">> string : " << m_str << std::endl;
std::cout << ">>-----------------------------------------------" << std::endl;
}
map::~map(){}
main function case 1 works, and case 2 gives the segmentation fault.
#include "map.hh"
int main(int argc, char const *argv[])
{
std::string id = "mapfile";
int action = 0;
if(argc > 1) action = std::stoi(argv[1]);
else {
std::string input;
std::cout << "Enter case (1 or 2): ";
std::cin >> input;
action = std::stoi(input);
}
switch (action)
{
case 1:
{
// This works 100% (no errors and it saves/reads class perfectly)
std::vector<double> l_vect = {0.1, 0.0, 0.6};
test_struct save_struct = {true, 5.0, l_vect};
map test_save(id);
test_save.show_file();
test_save.set_double(8.0);
test_save.set_str("save this string");
test_save.set_struct(save_struct);
test_save.show_file();
test_save.save_file();
map test_load(id);
test_load.load_file();
test_load.show_file();
}
break;
case 2:
{
// gives segmentation error at the end of the program
map test_load(id);
test_load.load_file();
test_load.show_file();
}
break;
default:
break;
}
return 0;
}

Related

Singleton Implementation: counter not incrementing as expected with multiple pointers to instance

The following program aims to instantiate and use the singleton pattern class proposed by Loki Astari and accepted as answer at the following link.
C++ Singleton design pattern
Note the addition of a simple counter, by way of the private counter variable, along with the increment() mutator, and getCtr() accessor methods.
Expected program output is:
0
1
Press any key to exit...
The actual output is
0
0
Press any key to exit...
Why is the counter in the singleton class not being incremented as expected?
What follows is a minimal, complete, and verifiable program, written to illustrate the issue.
#include "stdafx.h"
#include <iostream>
#include <string>
class S {
public:
static S & getInstance() {
static S instance;
instance.counter = 0; // initialize counter to 0
return instance;
}
S(S const &) = delete;
void operator = (S const &) = delete;
void increment() { ++counter; }
int getCtr() { return counter; }
private:
S() {}
int counter;
};
int main() {
S * s; // s is a pointer to the singleton object
S * t; // t is another pointer to the singleton object.
std::cout << s->getInstance().getCtr() << std::endl;
s->getInstance().increment(); // increment counter
std::cout << t->getInstance().getCtr() << std::endl;
std::cout << "Press any key to exit...";
std::cin.get();
return 0;
}
Thx, Keith :^)
your problem is you are initializing the counter inside the
getInstance() method
instead, initialize it inside the constructor
your code should be like the following,
#include <iostream>
#include <string>
class S {
public:
static S & getInstance() {
static S instance;
// instance.counter = 0; // initialize counter to 0
return instance;
}
S(S const &) = delete;
void operator = (S const &) = delete;
void increment() { ++counter; }
int getCtr() { return counter; }
private:
S() {counter =0;}
int counter;
};
int main() {
S * s; // s is a pointer to the singleton object
S * t; // t is another pointer to the singleton object.
std::cout << s->getInstance().getCtr() << std::endl;
s->getInstance().increment(); // increment counter
std::cout << t->getInstance().getCtr() << std::endl;
s->getInstance().increment(); // increment counter
std::cout << t->getInstance().getCtr() << std::endl;
s->getInstance().increment(); // increment counter
std::cout << t->getInstance().getCtr() << std::endl;
s->getInstance().increment(); // increment counter
std::cout << t->getInstance().getCtr() << std::endl;
s->getInstance().increment(); // increment counter
std::cout << t->getInstance().getCtr() << std::endl;
std::cout << "Press any key to exit...";
std::cin.get();
return 0;
}
then the Output will be
0
1
2
3
4
5
Press any key to exit...

Function Pointers in C++ Class Files

I've been trying to work with function pointers for quite a bit now, and to no avail. I've been working with a few friends to create a C++ 11 library to make creating ASCII games easier, and I've personally been working on creating a menu class. The beef of the class is complete, but one issue - I can't get the buttons to call functions. I always get the error:
terminate called after throwing an instance of 'std::bad_function_call'
what(): bad_function_call
This application has requested the Runtime to terminate it in an unusual way.
Please contact the application's support team for more information.
Obviously the error lies somewhere in the pointers, but I can't solve it for the life of me. Thanks for the help in advance.
Menu.h
#ifndef MENU_H
#define MENU_H
using namespace std;
#include <functional>
#include <string>
#include <map>
class Menu {
public:
int numberOfOptions;
map<int, string> options;
int currentSelection;
string title;
Menu();
Menu(int initialNumberOfOptions, map<int, string> initialOptions, int initialSelection);
void display();
void waitForInput();
void attachOptionAction(int option, void (*function)());
private:
map<int, void (*std::function<void()>)> optionActions;
void executeOptionAction(int option);
};
#endif
Menu.cpp
#include "Menu.h"
#include <windows.h>
#include <iostream>
#include <conio.h>
Menu::Menu(int initialNumberOfOptions, map<int, string> initialOptions, int initialSelection) {
title = "";
numberOfOptions = initialNumberOfOptions;
options = initialOptions;
currentSelection = initialSelection;
}
void Menu::display() {
SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), {0, 0});
for(int i = 0; i < 10; i++) {
cout << " " << endl;
}
SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), {0, 0});
if(title != "") {
cout << title << endl << endl;
}
for(int i = 0; i < numberOfOptions; i++) {
if(i == currentSelection - 1) {
cout << "[ " << options[i] << " ]" << endl;
} else {
cout << options[i] << endl;
}
}
waitForInput();
}
void Menu::waitForInput() {
char input;
while(!kbhit());
input = getch();
if(input == 72 && currentSelection > 1) {
currentSelection--;
} else if (input == 80 && currentSelection < numberOfOptions) {
currentSelection++;
} else if (input == 13) {
if(currentSelection == 1) {
executeOptionAction(1);
}
return;
}
display();
}
void Menu::attachOptionAction(int option, std::function<void()> function) {
optionActions[option] = function;
}
void Menu::executeOptionAction(int option) {
(optionActions[option])();
}
test.cpp
#include "Menu.h"
#include <unistd.h>
#include <iostream>
#include <iomanip>
#include <map>
void test() {
cout << "Hello, World!";
}
int main() {
map<int, string> options;
options[0] = "Play";
options[1] = "Help";
options[2] = "Quit";
Menu menu(3, options, 1);
menu.title = "ASCII Game Library 2015";
menu.display();
void (*actionPointer)() = NULL;
menu.attachOptionAction(1, (*actionPointer));
return 0;
}
This is wrong. I'm not even sure what's that supposed to be.
map<int, void (*std::function<void()>)> optionActions;
It should be:
map<int, std::function<void()>> optionActions;
This here is also wrong. It would be correct if you hadn't imported std into your current namespace.
void attachOptionAction(int option, void (*function)());
It should be:
void attachOptionAction(int option, const std::function<void()> & action);
This here is also wrong. You can't name your argument function after you imported std into your namespace.
void Menu::attachOptionAction(int option, std::function<void()> function)
It should be:
void Menu::attachOptionAction(int option, const std::function<void()> & action)
This here is also wrong. You don't check if the function exists or that a valid function pointer was assigned to it. Which you haven't.
(optionActions[option])();
It should be:
// Attempt to find the action!
map<int, std::function<void()>>::iterator action = optionActions.find(option);
// Did we find anything?
if (action == optionActions.end())
{
return;
}
// Is the function assigned to this action valid?
if (action->second)
{
action->second();
}
You are attaching a null function pointer to an action and try to call it. And since there's no validation it does exactly that. Which is why you get that exception:
void (*actionPointer)() = NULL;
menu.attachOptionAction(1, (*actionPointer));
But I'm not even sure how even managed to compile it :/
EDIT:
I hope you can find this example to be informative on what you're looking for.
#include <map>
#include <string>
#include <cstdlib>
#include <iostream>
#include <functional>
class Menu
{
protected:
typedef std::function<int (Menu &)> Callback;
typedef std::map<int, Menu> SubMenus;
public:
Menu()
: m_Id(0), m_Name(""), m_Handler(nullptr)
{
}
Menu(int id, const std::string & name, Callback clbk)
: m_Id(id), m_Name(name), m_Handler(clbk)
{
}
Menu & operator [] (int id)
{
return m_Childrens.at(id);
}
int Enter()
{
int result = 0;
if (m_Handler)
result = m_Handler(*this);
return result;
}
void Insert(const Menu & menu)
{
m_Childrens[menu.m_Id] = menu;
}
void Insert(int id, const std::string & name, Callback clbk)
{
m_Childrens[id] = Menu(id, name, clbk);
}
void Remove(int id)
{
m_Childrens.erase(id);
}
int GetId() const
{
return m_Id;
}
const std::string & GetName() const
{
return m_Name;
}
const Callback & GetHandler() const
{
return m_Handler;
}
bool IsChildren(int id) const
{
return (m_Childrens.find(id) != m_Childrens.cend());
}
Menu & GetChildren(int id)
{
return m_Childrens.at(id);
}
const SubMenus & GetChildrens() const
{
return m_Childrens;
}
private:
int m_Id;
std::string m_Name;
Callback m_Handler;
SubMenus m_Childrens;
};
void ClearScreen()
{
system("cls");
}
int SharedMenuDisplay(const Menu & menu)
{
ClearScreen();
std::cout << "Welcome to " << menu.GetName() << std::endl;
for (const auto & m : menu.GetChildrens())
{
std::cout << "> " << m.second.GetId() << " - " << m.second.GetName() << std::endl;
}
std::cout << "> 0 - Go Back" << std::endl;
std::cout << "Please select a sub menu: ";
int choice;
std::cin >> choice;
return choice;
}
int Menu_Home(Menu & menu)
{
int choice;
int result = 0;
do {
ClearScreen();
std::cout << "Welcome to " << menu.GetName() << std::endl;
for (const auto & m : menu.GetChildrens())
{
std::cout << "> " << m.second.GetId() << " - " << m.second.GetName() << std::endl;
}
std::cout << "> 0 - To Leave" << std::endl;
std::cout << "Please select a sub menu: ";
std::cin >> choice;
if (choice != 0 && menu.IsChildren(choice))
result = menu.GetChildren(choice).Enter();
} while (choice != 0);
return result;
}
int Menu_A(Menu & menu)
{
int choice;
int result = 0;
do {
choice = SharedMenuDisplay(menu);
if (choice != 0 && menu.IsChildren(choice))
result = menu.GetChildren(choice).Enter();
} while (choice != 0);
return result;
}
int Menu_A_SubMenu_X(Menu & menu)
{
ClearScreen();
std::cout << "You have selected " << menu.GetName() << std::endl;
std::cout << "> Type something and press Enter to go back..." << std::endl;
std::string str;
std::cin >> str;
return 0;
}
int Menu_A_SubMenu_Y(Menu & menu)
{
ClearScreen();
std::cout << "You have selected " << menu.GetName() << std::endl;
std::cout << "> Type something and press Enter to go back..." << std::endl;
std::string str;
std::cin >> str;
return 0;
}
int Menu_A_SubMenu_Z(Menu & menu)
{
ClearScreen();
std::cout << "You have selected " << menu.GetName() << std::endl;
std::cout << "> Type something and press Enter to go back..." << std::endl;
std::string str;
std::cin >> str;
return 0;
}
int Menu_B(Menu & menu)
{
int choice;
int result = 0;
do {
choice = SharedMenuDisplay(menu);
if (choice != 0 && menu.IsChildren(choice))
result = menu.GetChildren(choice).Enter();
} while (choice != 0);
return result;
}
int Menu_B_SubMenu_X(Menu & menu)
{
ClearScreen();
std::cout << "You have selected " << menu.GetName() << std::endl;
std::cout << "> Type something and press Enter to go back..." << std::endl;
std::string str;
std::cin >> str;
return 0;
}
int Menu_B_SubMenu_Y(Menu & menu)
{
ClearScreen();
std::cout << "You have selected " << menu.GetName() << std::endl;
std::cout << "> Type something and press Enter to go back..." << std::endl;
std::string str;
std::cin >> str;
return 0;
}
int Menu_B_SubMenu_Z(Menu & menu)
{
ClearScreen();
std::cout << "You have selected " << menu.GetName() << std::endl;
std::cout << "> Type something and press Enter to go back..." << std::endl;
std::string str;
std::cin >> str;
return 0;
}
int Menu_C(Menu & menu)
{
ClearScreen();
std::cout << "You have selected " << menu.GetName() << std::endl;
std::cout << "> Type something and press Enter to go back..." << std::endl;
std::string str;
std::cin >> str;
return 0;
}
int main(int argc, char **argv)
{
Menu home(-1, "Home", &Menu_Home);
home.Insert(1, "Menu Item A", &Menu_A);
home.Insert(2, "Menu Item B", &Menu_B);
home.Insert(3, "Menu Item C", &Menu_C);
home.GetChildren(1).Insert(1, "Sub Menu Item X", &Menu_A_SubMenu_X);
home.GetChildren(1).Insert(2, "Sub Menu Item Y", &Menu_A_SubMenu_Y);
home.GetChildren(1).Insert(3, "Sub Menu Item Z", &Menu_A_SubMenu_Z);
home[2].Insert(1, "Sub Menu Item X", &Menu_B_SubMenu_X);
home[2].Insert(2, "Sub Menu Item Y", &Menu_B_SubMenu_Y);
home[2].Insert(3, "Sub Menu Item Z", &Menu_B_SubMenu_Z);
return home.Enter();
}

Could somebody override this callBack()?

Usually, callBack() gotta be overridden in Child class.
but it doesn't. When the thread calls callBack(), it runs original method.
Is there any way to right this?
I compiled it with "g++ -o file source.cpp -lpthread"
I'm sure it is not about a compiler.
#include <iostream>
#include <unistd.h>
#include <pthread.h>
using namespace std;
class Parent
{
public:
virtual void callBack()
{
cout << "Original callBack() reported this: " << this << endl;
}
private:
pthread_t th = 0;
static void *th_func(void *arg)
{
Parent *p = (Parent*)arg;
cout << "*th_func() reported *arg: " << arg << endl;
p->callBack();
}
public:
Parent()
{
if(pthread_create(&th, NULL, th_func, (void*)this) < 0)
cerr << "thread not born." << endl;
else
cout << "thread has born." << endl;
}
~Parent()
{
if(th!=0)
pthread_join(th, NULL);
cout << "joined. Parent leaving." << endl;
}
};
class Child : public Parent
{
public:
void callBack()
{
cout << "child overridden." << endl;
}
Child() : Parent(){}
};
int main()
{
Child *ch = new Child();
delete ch;
return 0;
}
The problem with your code is that you are calling the thread function from inside the parent constructor. At that point, the Child object is not constructed yet (look up object initialisation order in C++), thus the only virtual function that it can call is the parent's.
From a C++ point of view, it's doing the right thing :).
In order to get your code to work, you have to separate the thread creation from the object creation, otherwise you'll never be able to call a function in a derived class.
Here's some more info from the C++ FAQ. And here's what Scott Meyers has to say about this topic.

Undefined reference to a method in another class file, how to fix?

I've been working on a program that will do a couple of equations in regards to audio, SPL, etc.
I decided to have the main class file present the user with an option to choose what equation he wants to do, while the equations are housed in another class file.
Atm, the main class file is setup just to test maxPeakSPL(), yet I can't get it to run.
main.cpp
//Kh[a]os
#include "equations.h"
#include <iostream>
void mainLoop();
int maxSPL = 0;
int main()
{
std::cout << "Created by Kh[a]os" << std::endl << std::endl;
mainLoop();
return 0;
}
void mainLoop()
{
std::cout << "hi";
maxSPL = equations::maxPeakSPL();
std::cout << std::endl << maxSPL << "db" << std::endl << std::endl;
}
equations.h
#ifndef EQUATIONS_H
#define EQUATIONS_H
#include <string>
class equations
{
public:
equations();
static int maxPeakSPL();
protected:
private:
};
#endif // EQUATIONS_H
equations.cpp
#include "equations.h"
#include <iostream>
#include <string>
equations::equations()
{
}
static int maxPeakSPL()
{
int Sens = 0;
double Distance = 0;
int Watts = 0;
int sWatts = 2;
int eWatts = 0;
double maxSPL = 0;
double counter = 0;
double wall = 0;
std::string corner = "";
bool v = true;
std::cout << "Sensitivity (db): " << std::endl;
std::cin >> Sens;
std::cout << "Amplification (watts): " << std::endl;
std::cin >> Watts;
std::cout << "Listening Distance (meters): " << std::endl;
std::cin >> Distance;
std::cout << "Distance from Wall (ft): " << std::endl;
std::cin >> wall;
std::cout << "Are you they in a corner? (y/n): " << std::endl;
std::cin >> corner;
maxSPL = Sens - (Distance*3 - 3);
while(v == true)
{
if (sWatts > Watts)
{
v = false;
eWatts = sWatts;
sWatts = sWatts/2;
Watts = Watts-sWatts;
counter = (double)Watts/(double)eWatts;
counter = counter*3;
maxSPL = maxSPL + counter;
}
if (v == true)
{
maxSPL = maxSPL + 3;
sWatts = sWatts*2;
}
}
if (wall <= 4)
maxSPL = maxSPL + 3;
if (corner == "Y" || corner == "YES" || corner == "y" || corner == "yes")
maxSPL = maxSPL + 3;
return maxSPL;
}
The error I get when I run it is: undefined reference to `equations::maxPeakSPL()'
I haven't a clue how to fix this, any assistance would be great. Thank you.
In your main, try putting the function before the main block. Include an underscore before the name of your directives/flags.

Printing a singly linked list using classes

I am making a program for singly linked lists using multiple files and classes.
I have to have a Node.h, LinkedList.h, Node.cpp, LinkedList.cpp, and a main.cpp
I was having other problems but now my printList() function just prints "List()" instead of "List(node 1, node2, etc...)"
I think my insert might be the problem because my searchNode() doesn't work right either, it always says node not found.
Here is the code I have: (I can't change the Node.h and LinkedList.h files)
Node.h:
//
// Node.h
// Linked Lists
//
#ifndef Linked_Lists_Node_h
#define Linked_Lists_Node_h
class Node
{
public:
Node(int data);
int data;
Node *next;
};
#endif
LinkedList.h:
//
// LinkedList.h
// Linked Lists
//
#ifndef Linked_Lists_LinkedList_h
#define Linked_Lists_LinkedList_h
#include "Node.h"
class LinkedList
{
private:
Node *head;
public:
LinkedList();
void addNode(int data);
void removeNode(int data);
bool searchNode(int data);
void printList();
};
#endif
Node.cpp
//
// Node.cpp
// Linked Lists
//
#include <iostream>
#include <cstdlib>
#include "LinkedList.h"
#include "Node.h"
using namespace std;
Node::Node(int data) {};
LinkedList.cpp
//
// LinkedList.cpp
// Linked Lists
//
#include <iostream>
#include <cstdlib>
#include "LinkedList.h"
#include "Node.h"
using namespace std;
LinkedList::LinkedList()
{
head = NULL;
}
void LinkedList::addNode(int data)
{
Node *newNode;
newNode->data = data;
newNode->next = NULL;
Node *tmp = head;
if(tmp != NULL)
{
while(tmp->next != NULL)
{
tmp = tmp->next;
}
tmp->next = newNode;
}
cout << "Node added" << endl;
printList();
}
void LinkedList::removeNode(int data)
{
Node *tmp = head;
if(tmp == NULL)
{
cout << "No node removed" << endl;
return;
}
if(tmp->next == NULL)
{
delete tmp;
head = NULL;
}
else
{
Node *previous;
do
{
if(tmp->data == data)
{
break;
}
previous = tmp;
tmp = tmp->next;
}
while(tmp != NULL);
previous->next = tmp->next;
delete tmp;
}
cout << "Node removed" << endl;
printList();
}
bool LinkedList::searchNode(int data)
{
Node *tmp = head;
while(tmp != NULL)
{
if(tmp->data == data)
{
cout << "Node found" << endl;
printList();
return true;
}
tmp = tmp->next;
}
cout << "Node not found" << endl;
printList();
return false;
}
void LinkedList::printList()
{
Node *tmp = head;
if(tmp == NULL)
{
cout << "List()" << endl;
return;
}
if(tmp->next == NULL)
{
cout << "List(" << tmp->data << ")";
}
else
{
do
{
cout << "List(" << tmp->data;
cout << ", ";
tmp = tmp->next;
}
while (tmp != NULL);
cout << ")" << endl;
}
}
main.cpp
//
// main.cpp
// Linked Lists
//
#include <iostream>
#include <cstdlib>
#include "LinkedList.h"
#include "Node.h"
#include "LinkedList.cpp"
using namespace std;
int main ()
{
LinkedList list;
int data;
int choice;
while(1)
{
cout << " Select:" << endl;
cout << "1 to add a node" <<endl;
cout << "2 to remove a node" << endl;
cout << "3 to search for a node" << endl;
cout << "4 to exit" << endl;
cout << endl;
cin >> choice;
switch(choice)
{
case 1: //insertion
cout << "Enter node: ";
cin >> data;
list.addNode(data); //add a node
break;
case 2: //deletion
cout << "Enter node: ";
cin >> data;
list.removeNode(data); //remove a node
break;
case 3: //search
cout << "Enter node: ";
cin >> data;
list.searchNode(data); //search for a node
break;
case 4:
exit(0); //exit the program
break;
default: //default case
cout << "Please enter a valid choice (1 - 4)!" << endl;
break;
}
}
return 0;
}
If you could help me figure out my problem I would greatly appreciate it.
You're not adding any nodes. If head is NULL, your add Node becomes:
void LinkedList::addNode(int data)
{
Node *newNode;
newNode->data = data;
newNode->next = NULL;
Node *tmp = head;
if(tmp != NULL)
{
//this never gets executed
}
cout << "Node added" << endl;
printList();
}
You need to treat this case (first insertion):
void LinkedList::addNode(int data)
{
Node *newNode;
newNode->data = data;
newNode->next = NULL;
Node *tmp = head;
if(tmp != NULL)
{
while(tmp->next != NULL)
{
tmp = tmp->next;
}
tmp->next = newNode;
}
else
{
head = newNode;
}
cout << "Node added" << endl;
printList();
}
This will create the head if it doesn't exist already.
Are you using a debugger? It would be much easier (for you) if you did.