Accessing an object vs. accessing a reference to the object

Everything seems to compile fine, but I'm getting a run-time error. What I don't understand is these are identical, the only difference being one is accessing an object directly and the other is accessing a reference to the object. For some reason I can declare the reference no problem, but as soon as I try to access it, it breaks.

Code:

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//part of cEntity.cpp
void cEntity::SetWornHead(cArmor * head)
{wornhead = head;}//wornhead declaration: cArmor * wornhead

cArmor* cEntity::GetWornHead(void)
{return wornhead;}

void cEntity::SetWornShoulders(cArmor shoulders)
{wornshoulders = shoulders;} //wornshoulder declaration: cArmor wornshoulders

cArmor cEntity::GetWornShoulders(void)
{return wornshoulders;}

//constructor
cEntity::cEntity(char* thisname)
{
    SetWornHead(&gArmorTravelersHead);
    SetWornShoulders(gArmorTravelersShoulders)
    GetWornHead()->GetArmorClass(); //threw that in just to see if it would work in the constructor, and it did.
}

---

Everything up to here works, butwhen i want to do something like this, I get the error

Code:

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void cEntity::SetAC(void)
{
        ac = GetWornHead()->GetArmorClass() + //doesnt work
                GetWornShoulders().GetArmorClass();//works
                //GetArmorClass() is a member of the class cArmor
}

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when gWornArmorTravelersHead falls out of scope wornhead is pointing to undefined behavior. I don't see any reason that wornhead needs to be a pointer.

Prefixing an & to a variable returns the address, it does not turn it into a reference. declaring a type with the & creates a reference variable.

Code:

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cArmor & wornhead = helm;

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makes any changes to wornhead change helm, realistically wornhead is just another name for helm and if at all possible the compiler will just treat it as such.

Code:

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trivial a;
trivial &b = a;
std::cout << a <<", " << b << std::endl;

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could legally, and probably should generate exactly the same code as

Code:

---

trivial a;
std::cout << a <<", " << a << std::endl;

---

The compiler usually can't quite do this, so it fakes it by using a pointer behind the scenes but it's a little bit more than just a "pointer that can never be null".

You don't have a reference in your code...
SetWornShoulders copies the object to your class member.
SetWornHead sets the pointer to the external object. And as it was said - in case that the object is destroyed by some reason you have a dangling pointer you cannot access.

Note that the SetWornShoulders can be rewritten in the following way:

Code:

---

void cEntity::SetWornShoulders(const cArmor& shoulders)
{wornshoulders = shoulders;}

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The logic stays the same, but instead of copying object twice - once in the temporary variable put into function and second time into your member variable, - you avoid first copy and leave only the second one

thx for the replies....for some reason I'm having a hard time getting a good grasp of referrers/pointers etc, most everything else has come w/ relative ease to me and I have been able to get it by just reading/using. Does anyone know of some good material on this subject specifically?(either excercises or reading material or anything really would be great).