I have 3 classes (Cat, HouseCat:Cat, Lion:Cat).
What I'm trying to do is change HouseCat's VTable to make HouseCat eat Meat instead of cat food.
Classes I Use:
class Cat
{
public:
int age = 2;
virtual void eat() {
cout << "Meat" << this->age << endl;
};
virtual void sound() {
cout << "Meow!" << this->age << endl;
};
};
class HouseCat : public Cat
{
public:
virtual void eat() {
cout << "Cat Food" << this->age << endl;
};
};
class Lion : public Cat
{
public:
virtual void sound() {
cout << "ROAR!" << this->age << endl;
};
};
I'm trying to edit those classes' VTable entries by a VTable struct I created.
static void __memcpy(void * set, void * data, int size){
DWORD old;
VirtualProtect(set, size, PAGE_EXECUTE_READWRITE, &old);
char*dest = (char*)set;
char*src = (char*)data;
for (int i = 0; i < size; i++)dest[i] = src[i];
VirtualProtect(set, size, old, &old);
}
struct VTable{
static VTable read(void * object){
VTable vt = *(VTable*)(object);
int i = 0;
while ((DWORD)vt.functions[i] != 0x0)
i++;
vt.size = i;
return vt;
}
void ** functions;
int size;
void redirectFunction(int i, void * redirect){
__memcpy(&functions[i], &redirect, 4);
}
};
I confirmed that VTable[0] = eat(), so i decided to try making a change on the Vtable like this :
int main(int argc, char* argv[])
{
Lion lion = Lion();
Cat base = Cat();
HouseCat home = HouseCat();
VTable lionVTable = VTable::read(&lion);
VTable baseVTable = VTable::read(&base);
VTable homeVTable = VTable::read(&home);
cout << "-------------- BEFORE EDIT -----------------" << endl
<< "Base:" << endl
<< (baseVTable.functions[0]) << endl
<< (baseVTable.functions[1]) << endl
<< "HomeCat:" << endl
<< (homeVTable.functions[0]) << endl
<< (homeVTable.functions[1]) << endl
<< "Lion:" << endl
<< (lionVTable.functions[0]) << endl
<< (lionVTable.functions[1]) << endl;
homeVTable.redirectFunction(0, lionVTable.functions[0]);
cout << "-------------- AFTER EDIT -----------------" << endl
<< "Base:" << endl
<< (baseVTable.functions[0]) << endl
<< (baseVTable.functions[1]) << endl
<< "HomeCat:" << endl
<< (homeVTable.functions[0]) << endl
<< (homeVTable.functions[1]) << endl
<< "Lion:" << endl
<< (lionVTable.functions[0]) << endl
<< (lionVTable.functions[1]) << endl;
pause();
cout << "---Base---" << endl << endl;
base.eat();
base.sound();
cout << "---Lion---" << endl << endl;
lion.eat();
lion.sound();
cout << "---Home---" << endl << endl;
home.eat();
home.sound();
cout << "---End---" << endl;
pause();
return 0;
}
It outputed;
-------------- BEFORE EDIT ----------------
Base:
0031106E
0031121C
HomeCat:
00311285
0031121C
Lion:
0031106E
003113F2
-------------- AFTER EDIT -----------------
Base:
0031106E
0031121C
HomeCat:
0031106E
0031121C
Lion:
0031106E
003113F2
You can see that HomeCat[0] changed from 0x311285->0x31106E
VMT.exe+11285 - E9 B6350000 - jmp VirtualMethodTable test.HouseCat::eat
[Cat Food]
->
VMT.exe+1106E - E9 ED450000 - jmp VirtualMethodTable test.Cat::eat
[Meat]
The problem is the output of the functions didnt change at all.
---Base---
Meat2
Meow!2
---Lion---
Meat2
ROAR!2
---Home---
Cat Food2
Meow!2
---End---
I'm using Visual Studio 2013. Release/Debug didnt make a difference either.
Did i do something wrong in my code or is it somekind of compiler stuff I'm missing?
I agree that this is a horrible hacky thing to do... however, to get it working I'd try changing your lion/base/home variables to be pointers to objects. Right now since they are not pointers, the compiler may be automatically calling the correct function without using the vtable (since it knows exactly what type the object is).
Related
I am new at programming using c++ and having some troubles creating my constructors & objects.
How can I access to my protected members like int p_iID in the Fahrzeug class?
I have to access them for both of my objects seperately.
I would be so happy if you could help me out with this.
class Fahrzeug {
private:
protected:
string p_sName;
int p_iID;
double p_dMaxGeschwindigkeit;
double p_dGesamtStrecke;
double p_dGesamtZeit;
double p_dZeit;
public:
virtual void vAusgeben(Fahrzeug* pFahrzeug1,Fahrzeug* pFahrzeug2);
virtual void vKopf();
virtual void vSimulieren(Fahrzeug *pFahrzeug, Fahrzeug *pFahrzeug2);
class PKW;
class PKW: public Fahrzeug{
PKW(const int p_iMaxID, string p_sName, double p_dMaxGeschwindigkeit, double p_dGesamtStrecke) {
p_iID = p_iMaxID;
this->p_sName = p_sName;
this->p_dMaxGeschwindigkeit = (p_dMaxGeschwindigkeit < 0) ? 0 : p_dMaxGeschwindigkeit;
this->p_dGesamtStrecke = p_dGesamtStrecke;
}
void vAusgeben(PKW pkw1, PKW pkw2) {
cout << "\n";
PKW pkw1;
PKW pkw2;
pkw1.vKopf();
cout << setw(5) << left << pkw1.p_iID<< " " << setw(10) <<pkw1.p_sName << setw(8) << " " << setw(15) << showpoint << pkw1.p_dMaxGeschwindigkeit << setw(3) << " " << pkw1.p_dGesamtStrecke; //Here I have the issue with pkw1.p_sName
cout << "\n";
cout << setw(5) << left << pkw2.p_iID << " " << setw(10) << pkw2.p_sName << setw(8) << " " << setw(15) << showpoint << pkw2.p_dMaxGeschwindigkeit << setw(3) << " " << pkw2.p_dGesamtStrecke;
cout << "\n";
}
}
void vAusgeben(PKW pkw1, PKW pkw2) {
You probably don't want to pass your PKW objects by value (or expect object slicing). Pass const references instead:
void vAusgeben(const PKW& pkw1, const PKW& pkw2) {
Also, why are you shadowing your 2 parameters with these local variables?
PKW pkw1; // ???
PKW pkw2; // ???
Aside from the issues raised in comments (and in another answer), there's a special rule for protected members that sometimes surprises people. An object of a derived type can access protected members of its base sub-object, but it can't access protected members of some other object. So:
struct B {
protected:
int i;
};
struct D : B {
void f(const B&);
};
void D::f(const B& b) {
i = 3; // okay, accessing my own protected member
b.i = 3; // no, access to protected member of different object not allowed
}
In the code in the question, the function PKW::vAusgeben can access its own copies of p_sName, p_dMaxGeschwindigkeit, and p_dGesamtStrecke, but it can't access pkw1.p_sName, pkw1.p_dMaxGeschwindigkeit, or pkw1.p_dGesamtStrecke.
I am posting my code below as tested, with the respective outputs shown in comments after the "cout"-statements, and my QUESTIONS as to the output that I do not understand indicated by "--> WHY". I am completely at a loss and I apologize in advance for my assumed stupidity that appears to prevent me from understanding what is going on.
#include <experimental/filesystem>
#include <iostream>
#include <vector>
using namespace std;
struct S
{
struct BASE
{
static double testval;
virtual void set_testval(double val) {testval = val;}
virtual double get_testval() {return testval;}
};
template<typename T>
struct DerivedTemplate : public BASE
{
static double testval;
void set_testval(double val) {testval = val;}
double get_testval() {return testval;}
};
struct DERIVED_01 : DerivedTemplate<DERIVED_01>
{
//...
};
struct DERIVED_02 : DerivedTemplate<DERIVED_02>
{
//...
};
struct DERIVED_03 : DerivedTemplate<DERIVED_03>
{
//...
};
vector<unique_ptr<BASE> > DERIVED_TYPES;
S();
}; // END struct S
S::S()
{
DERIVED_TYPES.resize(4);
}
double S::BASE::testval = 0;
template <typename T>
double S::DerivedTemplate<T>::testval = 1;
S s;
int main()
{
// Assign pointers to objects of derived structs to fields in vector of unique_ptr of base struct
{
unique_ptr<S::DERIVED_01> DERIVED (new S::DERIVED_01());
s.DERIVED_TYPES[0] = move(DERIVED);
}
{
unique_ptr<S::DERIVED_02> DERIVED (new S::DERIVED_02());
s.DERIVED_TYPES[1] = move(DERIVED);
}
{
unique_ptr<S::BASE> BASE (new S::BASE());
s.DERIVED_TYPES[2] = move(BASE);
}
{
unique_ptr<S::DERIVED_03> DERIVED (new S::DERIVED_03());
s.DERIVED_TYPES[3] = move(DERIVED);
}
cout << s.DERIVED_TYPES[0]->testval << endl; // Output: 0
cout << s.DERIVED_TYPES[0]->get_testval() << endl; // Output: 1 --> WHY is the output of this line "1" while that of the prior line was "0"?
// I assumed to be accessing the same member variable of the same object in both cases
cout << endl;
cout << s.DERIVED_TYPES[1]->testval << endl; // Output: 0
cout << s.DERIVED_TYPES[1]->get_testval() << endl; // Output: 1 --> WHY [same question]
cout << endl;
cout << s.DERIVED_TYPES[2]->testval << endl; // Output: 0
cout << s.DERIVED_TYPES[2]->get_testval() << endl; // Output: 0
cout << endl;
cout << s.DERIVED_TYPES[3]->testval << endl; // Output: 0
cout << s.DERIVED_TYPES[3]->get_testval() << endl; // Output: 1 --> WHY [same question]
cout << endl;
// Assign values to static member variables of derived struct objects
s.DERIVED_TYPES[0]->testval = 0.5;
s.DERIVED_TYPES[1]->testval = 1.5;
s.DERIVED_TYPES[2]->testval = 2.5;
s.DERIVED_TYPES[3]->testval = 2.75;
cout << s.DERIVED_TYPES[0]->testval << endl; // Output: 2.75
cout << s.DERIVED_TYPES[1]->testval << endl; // Output: 2.75
cout << s.DERIVED_TYPES[2]->testval << endl; // Output: 2.75
cout << s.DERIVED_TYPES[3]->testval << endl; // Output: 2.75 --> WHY are the outputs all "2.75"?
cout << endl;
s.DERIVED_TYPES[0]->set_testval(3.5);
s.DERIVED_TYPES[1]->set_testval(4.5);
s.DERIVED_TYPES[2]->set_testval(5.5);
s.DERIVED_TYPES[3]->set_testval(6.5);
cout << s.DERIVED_TYPES[0]->testval << endl; // Output: 5.5
cout << s.DERIVED_TYPES[0]->get_testval() << endl; // Output: 3.5
cout << endl;
cout << s.DERIVED_TYPES[1]->testval << endl; // Output: 5.5
cout << s.DERIVED_TYPES[1]->get_testval() << endl; // Output: 4.5
cout << endl;
cout << s.DERIVED_TYPES[2]->testval << endl; // Output: 5.5
cout << s.DERIVED_TYPES[2]->get_testval() << endl; // Output: 5.5
cout << endl;
cout << s.DERIVED_TYPES[3]->testval << endl; // Output: 5.5
cout << s.DERIVED_TYPES[3]->get_testval() << endl; // Output: 6.5
// Now, a "DIRECT ACCESS" of "testval" [s.DERIVED_TYPES[x]->testval]
// does not produce an output equal to the value assigned to
// s.DERIVED_TYPES[3]->testval, the last one assigned, but an
// output equal to the one assigned to the pointer pointing to the
// one object of struct BASE instead of "DERIVED_..."
// --> WHY?
cin.get();
return 0;
}
I have a class of light bulbs. There are methods and constructors in this class. There is even a destructor) The problem is that I have to determine and display information about class members with type "n" in the TEST() method (LED lamps).
To implement this task, he developed the gettype() method, which returns the type of an object, and, in fact, the TEST() method, which displays information about light bulbs.
The problem is that nothing works for me. I tried a lot of things, but it doesn’t work out for me to implement this task. I'm new to programming (
Code:
#include <iostream>
using namespace std;
class lamp
{
public:
// methods
void TEST(void);
char* gettype (void);
void INIT(void);
void SHOW(void);
// construcrors
lamp();
lamp(const char *t, int powe, const char *c, double cos);
lamp(const lamp & obj);
// destructor
~lamp();
private:
// data
char type[100]; // LED, energy-saving or incandescent lamp
int power; // LED lamp - "n"
char color[100];
double cost;
};
lamp::lamp() {
cout << "This object was created in the default constructor.\n";
strcpy(type, "");
power = 0;
strcpy(color, "");
cost = 0;
}
lamp::lamp(const char *t, int powe, const char *c, double cos) {
cout << "This object was created in the constructor with parameters.\n";
strcpy(type, t); //*t
power = powe;
strcpy(color, c); //*c
cost = cos;
}
lamp::lamp(const lamp & obj) {
cout << "This object was created in the copy constructor.\n";
strcpy(type, obj.type);
power = obj.power;
strcpy(color, obj.color);
cost = obj.cost;
}
lamp::~lamp() {
cout << "Deletion of object by destructor.\n";
}
void lamp::SHOW(void) {
cout << "Lamp Information:\n";
cout << "\nType > " << type;
cout << "\nPower > " << power;
cout << "\nColor > " << color;
cout << "\nCost > " << cost << endl;
}
void lamp::INIT(void) {
cout << "Enter lamp information:\n";
cout << "\nType (if LED, then n) > "; cin >> type;
cout << "\nPower > "; cin >> power;
cout << "\nColor > "; cin >> color;
cout << "\nCost > "; cin >> cost;
}
char* lamp::gettype (void) {
return type;
}
void lamp::TEST(void) {
cout << "\nType > " << type;
cout << "\nPower > " << power;
cout << "\nColor > " << color;
cout << "\nCost > " << cost << endl;
}
void main() {
setlocale(0, "");
// default constructor for 1 class instance
lamp l1;
cout << "Entering data for the first product." << endl;
l1.INIT();
// constructor with parameters for 2 class instances
cout << endl << "Information about the second object: \n";
lamp l2("n", 950, "yellow", 1580);
// copy constructor for the third object
cout << endl << "Information about the third object: \n";
lamp l3(l2);
// Derived information about all the lamps using the method SHOW
l1.SHOW();
l2.SHOW();
l3.SHOW();
// I create an array of two objects using the default constructor
lamp la[2];
I enter data into an array of objects using the method INIT
cout << "Fill an array of objects with 2 elements." << endl;
for(int i = 0; i < 2; i++) {
la[i].INIT();
}
// I output data from an array of objects using the method SHOW
cout << "Showing items." << endl;
for (int i = 0; i < 2; i++) {
la[i].SHOW();
}
// looking for and displaying information about LED lamps
cout << "Search and display information about LED lamps." << endl;
for (int i = 0; i < 3; i++) {
if (la[i].gettype() == "n") {
cout << endl << " lamp number : " << (i + 1) << endl;
la[i].TEST();
cout << endl;
}
}
system("pause");
}
There are several errors in your code：
strcpy is included in <cstring> which is missed. You need to add it in the beginning:
#include <cstring>
main() function should be declared as int main() and you need to add a return statement
int main() {
//YOUR CODE HERE
return 0;
}
You missed a comment sign at line 104
lamp la[2];
//I enter data into an array of objects using the method INIT
cout << "Fill an array of objects with 2 elements." << endl;
After fixed, your code should be able to run.
Hi this is the header file for my base class Ranger, and in it I have protected variables fov_, usb_ ... that I wish to access with my getter functions, I have three child classes on this one.
Ranger.h
#ifndef RANGER_H
#define RANGER_H
using namespace std;
class Ranger
{
//private contructor prevents contruction of base class
Ranger();
public:
void setBaud(int baud);
virtual void setFOV(int fov) = 0;
void setSamp(int sam);
int getFOV();
int getBaud();
int getMaxRange();
int getUSB();
protected:
//protected variables that are each indivdualy owned by each sensor
int fov_;
int maxRange_;
int usb_;
int baud_;
int samp_;
double data[];
//protected contructors for the child classes to use to set fixed parameters
Ranger(int fov, int maxRange, int port);
Ranger(int maxRange, int port);
};
#endif // RANGER_H
This is my cpp file for the base class that includes the getter files, it just has a return of the portected variables.
Ranger::Ranger()
{
}
Ranger::Ranger(int fov, int maxRange, int port)
{
fov_ = fov;
maxRange_ = maxRange;
usb_ = port;
}
Ranger::Ranger(int maxRange, int port)
{
maxRange_ = maxRange;
usb_ = port;
}
void Ranger::setBaud(int baud)
{
switch(baud)
{
case 0: baud_ = 38400; break;
case 1: baud_ = 115200; break;
default: baud_ = 38400; break;
}
}
void Ranger::setSamp(int sam)
{
samp_ = sam;
}
int Ranger::getFOV()
{
return fov_;
}
int Ranger::getBaud()
{
return baud_;
}
int Ranger::getMaxRange()
{
return maxRange_;
}
int Ranger::getUSB()
{
return usb_;
}
And in my main I want to access the protected variables from the base class to prevent re writting code, so each childs variables are protected in the base class. I try to access these by las.getFOV() but I get a segmentation fault error meaning I don't have access to them, and I don't quite understand why.
main.cpp
int main( int argc, char ** argv)
{
Laser las;
int baud;
cout << "Baud:" << endl;
cout << "0 - 38400" << endl;
cout << "1 - 115200" << endl;
cin >> baud;
las.setBaud(baud);
cout << "Baud for Lazer sensor is "+las.getBaud() << endl;
cout << "Lazer sensor created..." << endl;
cout << "Lazer's FOV: " + las.getFOV() << endl;
cout << "Lazer's Max Range: " + las.getMaxRange() << endl;
cout << "Lazer's Port: " + las.getUSB() << endl;
Radar rad;
int baud2;
cout << "Baud:" << endl;
cout << "0 - 38400" << endl;
cout << "1 - 115200" << endl;
cin >> baud2;
rad.setBaud(baud2);
cout << "Baud for Radar sensor is "+rad.getFOV() << endl;
int fov;
cout << "Feild of View Of Radar:" << endl;
cout << "0 - 20 degrees" << endl;
cout << "1 - 40 degrees" << endl;
cin >> fov;
rad.setFOV(fov);
cout << "FOV is set to " + rad.getFOV() << endl;
cout << "Radar sensor created..." << endl;
cout << "Radar's FOV: ' " + rad.getFOV() << endl;
cout << "Radar's Max Range: " + rad.getMaxRange() << endl;
cout << "Radar's Port: " + rad.getUSB() << endl;
Sonar son;
//rad.setFOV(user);
}
and here is one of the child class's cpp file for reference (Lazer)
laser.cpp
#include "laser.h"
Laser::Laser() : Ranger(180,8,0)
{
};
void Laser::setFOV(int fov)
{
fov_ = fov;
}
laser.h
#ifndef LASER_H
#define LASER_H
#include "ranger.h"
#include "rng.h"
class Laser : public Ranger
{
public:
Laser();
void setFOV(int fov);
};
#endif // LASER_H
Thanks everyone who commented, I understand I put way too much code to help you guys out, sorry about that I'll know for next time, and thankyou to letting me know the difference between the errors, I've done more research and found that the issue was when I was printing it out you can't use operators like:
cout<<""+function()<<endl;
Instead you need to separate the functions from the array like so:
cout<<""<<function()<<endl;
Thanks guys.
Long story short: The program I'm working on is a rogue like - even though that isn't really needed for this question.
Here's the hierarchy tree for my classes related to this question:
Entity
Item Creature
Weapon Armor
I have several virtual functions declared in Entity, which are also virtual in the classes derived from it.
I'm not sure how to word my question, but I'll explain the problem and post the code below. I have a factory type class, called ItemFactory, that opens an xml file and uses a simple parser that I made - and creates Item objects and sets their values. It has a method that returns an Item pointer. In my main file, I declare/define an ItemFactory object. When an Item needs to be dropped in the game, I use a pointer, that is of type, Item,
and call the method to randomly choose an Item to point to. All of this works perfectly..
Here's the problem. Entity has a virtual method called dumpObject() which prints the state of the variables it has. dumpObject() is also virtual in Item. When it's called from an Item, the method first calls Entity's dump with this:
Entity::dumpObject();
Then it dumps it's own variables.. I do the same for Weapon and Armor except using this:
Item::dumpObject();
My Question:
Since the ItemFactory holds both - Weapons and Armor, and the pointer in the main program points to an Item, shouldn't calling "itemPointer->dumpObject();" dump the values for Weapon/Armor (depending which it is pointing to..) which would also dump the values in Item which would also dump the values in Entity?
When I run the code, the only part that gets dumped is the part in Item and Entity.
Let me know if I need to provide more detail. Any suggestions? Thanks!
Here's the Code Snippets
I have the headers included, just tried to minimize the amount of code that I'm posting
Item.cpp
void Item::dumpObject(){
cout << "Item:" << endl;
dumpObjectData();
}
void Item::dumpObjectData(){
Entity::dumpObjectData();
cout << " [Weight] " << getWeight() << endl;
cout << " [Value] " << getValue() << endl;
cout << " [Quantity] " << getQuantity() << endl;
cout << " [Enchantment] " << getEnchantment() << endl;
}
Entity.cpp
void Entity::dumpObject(){
cout << "Entity:" << endl;
dumpObjectData();
}
void Entity::dumpObjectData(){
XMLSerializable::dumpObjectData(); //XMLSerialization handles parsing
cout << " [Name] " << getName() << endl;
cout << " [DisplayChar] " << getDisplayChar() << endl;
cout << " [Properties] " << endl;
for( auto it = m_vProperties.begin(); it != m_vProperties.end();it++ ){
cout << " - " << (*it) << endl;
}
}
Weapon.cpp
void Weapon::dumpObject(){
cout << "Weapon:" << endl;
dumpObjectData();
}
void Weapon::dumpObjectData(){
Item::dumpObjectData();
cout << " [Damage] " << getDamage() << endl;
cout << " [Range] " << getRange() << endl;
cout << " [Accuracy] " << getAccuracy() << endl;
cout << " [AmmoType] " << getAmmoType() << endl;
cout << " [Type] " << getType() << endl;
}
Armor.cpp
void Armor::dumpObject(){
cout << "Armor:" << endl;
dumpObjectData();
}
void Armor::dumpObjectData(){
cout << "calls to dump item data"<<endl;
Item::dumpObjectData();
cout << "calls to dump armor"<<endl;
cout << " [Type] " << getType() << endl;
cout << " [Slot] " << getSlot() << endl;
cout << " [ArmorValue] " << getArmorValue() << endl;
}
Main
ItemFactory myItems = ItemFactory::instance();
Item * pItem1 = myItems.generateItem();
pItem1->dumpObject();
Headers
Entity.h
#include "XMLSerializable.h"
#include <vector>
class Entity : public XMLSerializable {
public:
Entity(void);
virtual ~Entity(void);
virtual void dumpObject();
virtual void dumpObjectData();
};
Item.h
#include "Entity.h"
class Item : public Entity{
public:
Item(void);
virtual ~Item(void);
virtual void dumpObject();
virtual void dumpObjectData();
};
Weapon.h
#include "Item.h"
class Weapon : public Item {
public:
Weapon(void);
virtual ~Weapon(void);
virtual void dumpObject();
virtual void dumpObjectData();
};
Armor.h
#include "Item.h"
class Armor : public Item {
public:
Armor(void);
virtual ~Armor(void);
virtual void dumpObject();
virtual void dumpObjectData();
};
ItemFactory.cpp
ItemFactory & ItemFactory::instance(){
static ItemFactory myObj;
return myObj;
}
ItemFactory::ItemFactory(){
m_mtRandom.seed( time(NULL) );
fstream xmlFile;
xmlFile.open("items.xml");
vector<XMLSerializable*> pObjects;
parseXML(xmlFile, pObjects);
XMLSerializable * pObject;
for(auto it = pObjects.begin(); it != pObjects.end(); it++){
pObject = (*it);
Item * pItem = dynamic_cast<Item*>(pObject);
if (pItem != NULL){
m_vItems.push_back(pItem);
}
}
}
ItemFactory::~ItemFactory(){
}
Item * ItemFactory::generateItem() {
vector<Item*> tempItems;
for(auto it = m_vItems.begin(); it != m_vItems.end(); it++){
tempItems.push_back((*it));
}
int randomItem = (m_mtRandom() % (m_vItems.size() - 1));
Item * pItem = tempItems.at(randomItem);
Item * pReturnValue = new Item(*pItem);
return pReturnValue;
}
Now that I just did all that work, I don't think any of the code except maybe Main was necessary.. Lol I'm guessing my logic for the pointer in Main is wrong?
Well here's your problem:
Item * pReturnValue = new Item(*pItem);
This is giving you a shallow copy so that you do not get an Armor or Weapon.
If you need to do a copy given only a base class instance, define a clone method in the base class.
It looks like you are trying to use the prototype pattern, so you do want to create new instances?
class Entity : public XMLSerializable {
public:
Entity(void);
virtual ~Entity(void);
virtual Entity* clone() const { return new Entity(*this);}
virtual void dumpObject();
virtual void dumpObjectData();
};
class Armor : public Item {
public:
Armor(void);
virtual ~Armor(void);
virtual Armor* clone() const { return new Armor (*this);}
virtual void dumpObject();
virtual void dumpObjectData();
};
Note the use of covariant return values for clone(). I.e. The return values do differ but as the method signature matches and the return values are derived from one another, the call is virtual.
You then can write:
Item * pReturnValue = pItem->clone();
See: Wikipedia for background on the Prototype pattern.