C++ Class/Function interaction - c++

Question

I'm fairly new to c++ classes and exactly how they work, but I'm trying to figure what issues I have with this code. What I'm trying to do is that the class handle the dice object, how many faces the die has and the value of the roll. Then use those values later on in the code. I know I've done something fundamentally wrong here I'm just not sure what.
The class header is:
class Dice {
private :
int face ;
int value ;
public:
Dice()
{
face = 6;
}
Dice(int faceVal)
{
face = faceVal;
}
Dice(Dice &other)
{
face = other.face;
}
Dice& operator=(const Dice &rhs);
int roll() ;
int getValue() const { return value; }
int getFace() const { return face; }
} ;
Dice& Dice::operator=(const Dice &rhs)
{
face = rhs.face;
return *this;
}
#endif
The functions/methods that are being used:
int Dice::roll()
{
srand((unsigned)time(0));
int randomNumber = 1 + rand() % 5;
value = randomNumber;
return randomNumber;
}
int rollAll(Dice cup[], int n)
{
int faces = 0;
for(int i = 0; i < n; i++)
faces += cup[i].roll();
return sum ;
}
And the entrance into them from the main function is:
total = rollAll(cup,2) ;
for (int i = 0 ; i < 2 ; i++ )
(arr[i] = cup[i].getValue());

Answer 1

The glaring issue with your code is that your copy constructor and assignment operator are incorrect. You are failing to actually copy the object fully, as you are missing the value member in the copying operations.
Dice(Dice &other)
{
face = other.face;
// where is the `value` member?
}
So where is the copy of the value member being made? If you miss any members during the copy, your program will be using "half-copies" masquerading as real copies. These types of bugs, where you don't copy everything, are some of the toughest to find.
This is one reason why you should not get involved in writing copy/assignment functions unless it is absolutely required. In your case, the compiler generated copy constructor / assignment operator will do the job correctly without you having to write one.