Copying pointers to objects with tables - c++

Question

I have a problem when copying pointers to objects that contain tables... Some information is kept (strings, for example skillName), but the tables contain new, random data. I tried several things, but I still don't know what's wrong and how to do it... Help me, please. :)
EDIT: I've edited whole post, and as WhozCraig suggested made it MCVE (at least I tried).
Everything now is in this block of code, so you can just copy it and see it for yourself. For some reason the problem is in different location now, but it's still the same...
#include <iostream>
#include <string>
using namespace std;
class Skill
{
protected:
int const maxSkillLevel;
short skillLevel;
string skillName;
public:
Skill(string skillName) : maxSkillLevel(5){
skillLevel = 0;
this->skillName = skillName;
}
virtual ~Skill(){}
virtual int getMaxDmg(int i){ return 0; };
void increaseSkillLevel(int);
string getSkillName(){ return skillName; }
};
class OffensiveSkill : public Skill{
protected:
int *maxDmg;
public:
OffensiveSkill(string skillName, int maxDmg[]) : Skill(skillName){
this->maxDmg = maxDmg;
}
~OffensiveSkill(){}
int getMaxDmg(int i){ return maxDmg[i]; }
};
class Role{
protected:
string roleName;
Skill **skills;
public:
Role(string roleName){
skills = new Skill*[3];
this->roleName = roleName;
}
Role(Role* role){
this->skills = role->getSkills();
this->roleName = role->getRoleName();
}
Skill **getSkills(){ return skills; }
string getRoleName(){ return roleName; }
void setSkills(Skill* s1){ skills[0] = s1; }
};
class RoleGenerator{
protected:
Role *role;
public:
RoleGenerator(){
role = new Role("assassin");
int maxDmg[5] = { 30, 45, 60, 75, 90 };
OffensiveSkill* assassinate = new OffensiveSkill("Assassinate", maxDmg);
role->setSkills(assassinate);
cout << "maxDmg in RoleGenerator " << role->getSkills()[0]->getMaxDmg(0) << endl;
}
Role *getRoles(){ return role; }
};
int main(){
RoleGenerator* rg = new RoleGenerator();
Role *role = rg->getRoles();
cout << "maxDmg in main " << role->getSkills()[0]->getMaxDmg(0) << endl;
Role *copied = new Role(role);
//maxDmg here is different
cout << "maxDmg in after copying " << role->getSkills()[0]->getMaxDmg(0) << endl;
//but skill name is copied correctly
cout << "skill name " << role->getSkills()[0]->getSkillName() << endl;
}

Answer 1

The local array in RoleGenerator:: RoleGenerator()
int maxDmg[5] = { 30, 45, 60, 75, 90 };
is being passed as-address to:
OffensiveSkill* assassinate = new OffensiveSkill("Assassinate", maxDmg);
where that address is saved via:
this->maxDmg = maxDmg;
After RoleGenerator:: RoleGenerator() returns maxDmg is no longer valid to address. Dereferencing the saved address later invokes undefined behavior.
If a copy is sufficient one way to make this trivial is by copying the array into a simple member array or vector. There are multiple ways to do this. A decent arbitrary-length solution using a vector would be something like this:
#include <vector>
class OffensiveSkill : public Skill {
protected:
std::vector<int> maxDmg;
public:
template<size_t N>
OffensiveSkill(string skillName, int (&dmg)[N])
: Skill(skillName)
, maxDmg(dmg, dmg+N)
{
}
int getMaxDmg(int i) const { return maxDmg[i]; }
};
That alone should work as a drop-in replacement for your exiting constructor and class definition. If needed you can offer up additional flexibility by providing alternate constructors, such as one that allows beginning and end iterators directly passable to maxDmg construction, an int* and size_t length, etc.
And I would suggest you modify your indexing member getMaxDmg() to (a) range check the input value and toss an exception if out of range, and (b) use an unsigned data type (such as std::size_t) for your indexes. Unrelated to your question, but worth considering.

Answer 2

This is looking strange:
skills[0] = static_cast<OffensiveSkill*>(roleSkills[0]);
You would need to include more of your code.
But, based on the limited information, looks like you are better off with a copy constructor that is custom. A compiler generated copy-constructor won't perform deep-copy for you.